Merge branch 'master' into callback_preemption

.gitignore

@@ -5,3 +5,4 @@ tags
 .ctags
 *.bk
 TODO.txt
+*.rustfmt

Cargo.toml

@@ -17,7 +17,6 @@ repository = "gyscos/Cursive"
 enum-map = "0.2.24"
 enumset = "0.3.3"
 log = "0.4"
-num = "0.1"
 owning_ref = "0.3.3"
 toml = "0.4"
 unicode-segmentation = "1.0"
@@ -26,6 +25,10 @@ xi-unicode = "0.1.0"
 libc = "0.2"
 chan = "0.1"
 
+[dependencies.num]
+default-features = false
+version = "0.1"
+
 [dependencies.maplit]
 optional = true
 version = "1.0.0"

examples/colors.rs

@@ -1,9 +1,9 @@
 extern crate cursive;
 
-use cursive::{Cursive, Printer};
 use cursive::theme::{Color, ColorStyle};
 use cursive::view::Boxable;
 use cursive::views::Canvas;
+use cursive::{Cursive, Printer};
 
 // This example will draw a colored square with a gradient.
 //
@@ -19,7 +19,11 @@ use cursive::views::Canvas;
 fn main() {
     let mut siv = Cursive::default();
 
-    siv.add_layer(Canvas::new(()).with_draw(draw).fixed_size((20, 10)));
+    siv.add_layer(
+        Canvas::new(())
+            .with_draw(draw)
+            .fixed_size((20, 10)),
+    );
 
     siv.add_global_callback('q', |s| s.quit());
 

examples/dialog.rs

@@ -1,7 +1,7 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::views::{Dialog, TextView};
+use cursive::Cursive;
 
 fn main() {
     // Creates the cursive root - required for every application.

examples/edit.rs

@@ -1,8 +1,8 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::traits::*;
 use cursive::views::{Dialog, EditView, TextView};
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();

examples/hello_world.rs

@@ -1,7 +1,7 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::views::TextView;
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();

examples/key_codes.rs

@@ -1,15 +1,19 @@
 extern crate cursive;
 
-use cursive::{Cursive, Printer};
 use cursive::event::{Event, EventResult};
 use cursive::traits::*;
+use cursive::{Cursive, Printer};
 
 // This example define a custom view that prints any event it receives.
 // This is a handy way to check the input received by cursive.
 
 fn main() {
     let mut siv = Cursive::default();
-    siv.add_layer(KeyCodeView::new(10).full_width().fixed_height(10));
+    siv.add_layer(
+        KeyCodeView::new(10)
+            .full_width()
+            .fixed_height(10),
+    );
 
     siv.run();
 }

examples/linear.rs

@@ -1,9 +1,9 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::align::HAlign;
 use cursive::traits::*;
 use cursive::views::{Dialog, DummyView, LinearLayout, TextView};
+use cursive::Cursive;
 
 // This example uses a LinearLayout to stick multiple views next to each other.
 

examples/list_view.rs

@@ -1,9 +1,10 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::traits::*;
-use cursive::views::{Checkbox, Dialog, EditView, LinearLayout, ListView,
-                     SelectView, TextView};
+use cursive::views::{
+    Checkbox, Dialog, EditView, LinearLayout, ListView, SelectView, TextView,
+};
+use cursive::Cursive;
 
 // This example uses a ListView.
 //

examples/logs.rs

@@ -1,8 +1,8 @@
 extern crate cursive;
 
-use cursive::{Cursive, Printer};
 use cursive::traits::*;
 use cursive::vec::Vec2;
+use cursive::{Cursive, Printer};
 use std::collections::VecDeque;
 use std::sync::mpsc;
 use std::thread;
@@ -87,8 +87,11 @@ impl View for BufferView {
 
     fn draw(&self, printer: &Printer) {
         // Print the end of the buffer
-        for (i, line) in
-            self.buffer.iter().rev().take(printer.size.y).enumerate()
+        for (i, line) in self.buffer
+            .iter()
+            .rev()
+            .take(printer.size.y)
+            .enumerate()
         {
             printer.print((0, printer.size.y - 1 - i), line);
         }

examples/markup.rs

@@ -1,18 +1,21 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::theme::BaseColor;
 use cursive::theme::Color;
 use cursive::theme::Effect;
 use cursive::theme::Style;
 use cursive::utils::markup::StyledString;
 use cursive::views::{Dialog, TextView};
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();
 
     let mut styled = StyledString::plain("Isn't ");
-    styled.append(StyledString::styled("that ", Color::Dark(BaseColor::Red)));
+    styled.append(StyledString::styled(
+        "that ",
+        Color::Dark(BaseColor::Red),
+    ));
     styled.append(StyledString::styled(
         "cool?",
         Style::from(Color::Light(BaseColor::Blue)).combine(Effect::Bold),

examples/menubar.rs

@@ -1,10 +1,10 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::event::Key;
 use cursive::menu::MenuTree;
 use cursive::traits::*;
 use cursive::views::Dialog;
+use cursive::Cursive;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 // This examples shows how to configure and use a menubar at the top of the

examples/mines/game.rs

@@ -64,7 +64,8 @@ impl Board {
     }
 
     fn get_mut(&mut self, pos: Vec2) -> Option<&mut Cell> {
-        self.cell_id(pos).map(move |i| &mut self.cells[i])
+        self.cell_id(pos)
+            .map(move |i| &mut self.cells[i])
     }
 
     pub fn cell_id(&self, pos: Vec2) -> Option<usize> {

examples/mines/main.rs

@@ -3,13 +3,13 @@ extern crate rand;
 
 mod game;
 
-use cursive::Cursive;
-use cursive::Printer;
 use cursive::direction::Direction;
 use cursive::event::{Event, EventResult, MouseButton, MouseEvent};
 use cursive::theme::{BaseColor, Color, ColorStyle};
 use cursive::vec::Vec2;
 use cursive::views::{Button, Dialog, LinearLayout, Panel, SelectView};
+use cursive::Cursive;
+use cursive::Printer;
 
 fn main() {
     let mut siv = Cursive::default();
@@ -189,7 +189,9 @@ impl cursive::view::View for BoardView {
                 Cell::Unknown => "[]",
                 Cell::Flag => "()",
                 Cell::Visible(n) => {
-                    ["  ", " 1", " 2", " 3", " 4", " 5", " 6", " 7", " 8"][n]
+                    [
+                        "  ", " 1", " 2", " 3", " 4", " 5", " 6", " 7", " 8"
+                    ][n]
                 }
             };
 

examples/mutation.rs

@@ -1,9 +1,9 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::traits::*;
 use cursive::view::{Offset, Position};
 use cursive::views::{Dialog, OnEventView, TextView};
+use cursive::Cursive;
 
 // This example modifies a view after creation.
 

examples/position.rs

@@ -1,9 +1,9 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::view::Position;
 use cursive::views::LayerPosition;
 use cursive::views::TextView;
+use cursive::Cursive;
 
 /// Moves top layer by the specified amount
 fn move_top(c: &mut Cursive, x_in: isize, y_in: isize) {

examples/progress.rs

@@ -1,10 +1,10 @@
 extern crate cursive;
 extern crate rand;
 
-use cursive::Cursive;
 use cursive::traits::*;
-use cursive::views::{Button, Dialog, LinearLayout, ProgressBar, TextView};
 use cursive::utils::Counter;
+use cursive::views::{Button, Dialog, LinearLayout, ProgressBar, TextView};
+use cursive::Cursive;
 use rand::Rng;
 use std::cmp::min;
 use std::thread;
@@ -87,7 +87,11 @@ fn phase_2(s: &mut Cursive) {
     // Let's prepare the progress bars...
     let mut linear = LinearLayout::vertical();
     for c in &counters {
-        linear.add_child(ProgressBar::new().max(n_max).with_value(c.clone()));
+        linear.add_child(
+            ProgressBar::new()
+                .max(n_max)
+                .with_value(c.clone()),
+        );
     }
 
     s.pop_layer();

examples/radio.rs

@@ -1,7 +1,7 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::views::{Dialog, DummyView, LinearLayout, RadioGroup};
+use cursive::Cursive;
 
 // This example uses radio buttons.
 

examples/refcell_view.rs

@@ -1,8 +1,8 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::view::{Boxable, Identifiable};
 use cursive::views::{Dialog, EditView, LinearLayout, TextView};
+use cursive::Cursive;
 
 // This example shows a way to access multiple views at the same time.
 
@@ -38,6 +38,10 @@ fn on_edit(siv: &mut Cursive, _content: &str, _cursor: usize) {
     let matches = edit_1.get_content() == edit_2.get_content();
 
     siv.call_on_id("match", |v: &mut TextView| {
-        v.set_content(if matches { "match" } else { "no match" })
+        v.set_content(if matches {
+            "match"
+        } else {
+            "no match"
+        })
     });
 }

examples/scroll.rs

@@ -0,0 +1,39 @@
+extern crate cursive;
+
+use cursive::traits::Boxable;
+use cursive::views::{Button, Canvas, Dialog, LinearLayout, ScrollView};
+use cursive::Printer;
+
+fn main() {
+    let mut siv = cursive::Cursive::default();
+
+    siv.add_layer(
+        Dialog::around(
+            ScrollView::new(
+                LinearLayout::vertical()
+                    .child(Button::new("Foo", |s| {
+                        s.add_layer(Dialog::info("Ah"))
+                    }))
+                    .child(
+                        Canvas::new(()).with_draw(draw).fixed_size((120, 40)),
+                    )
+                    .child(Button::new("Bar", |s| {
+                        s.add_layer(Dialog::info("Uh"))
+                    })),
+            ).scroll_x(true),
+        ).fixed_size((60, 30)),
+    );
+
+    siv.add_global_callback('q', |s| s.quit());
+
+    siv.run();
+}
+
+fn draw(_: &(), p: &Printer) {
+    for x in 0..p.size.x {
+        for y in 0..p.size.y {
+            let c = (x + 6 * y) % 10;
+            p.print((x, y), &format!("{}", c));
+        }
+    }
+}

examples/select.rs

@@ -1,10 +1,10 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::align::HAlign;
 use cursive::event::EventResult;
 use cursive::traits::*;
 use cursive::views::{Dialog, OnEventView, SelectView, TextView};
+use cursive::Cursive;
 
 // We'll use a SelectView here.
 //

examples/slider.rs

@@ -1,8 +1,8 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::traits::*;
 use cursive::views::{Dialog, SliderView};
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();

examples/terminal_default.rs

@@ -1,8 +1,8 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::theme::{Color, PaletteColor, Theme};
 use cursive::views::TextView;
+use cursive::Cursive;
 
 // This example sets the background color to the terminal default.
 //

examples/text_area.rs

@@ -1,9 +1,9 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::event::{Event, Key};
 use cursive::traits::*;
 use cursive::views::{Dialog, EditView, OnEventView, TextArea};
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();
@@ -19,7 +19,9 @@ fn main() {
     );
 
     // We'll add a find feature!
-    siv.add_layer(Dialog::info("Hint: press Ctrl-F to find in text!"));
+    siv.add_layer(Dialog::info(
+        "Hint: press Ctrl-F to find in text!",
+    ));
 
     siv.add_global_callback(Event::CtrlChar('f'), |s| {
         // When Ctrl-F is pressed, show the Find popup.
@@ -35,10 +37,10 @@ fn main() {
                             .min_width(10),
                     )
                     .button("Ok", |s| {
-                        let text = s.call_on_id(
-                            "edit",
-                            |view: &mut EditView| view.get_content(),
-                        ).unwrap();
+                        let text =
+                            s.call_on_id("edit", |view: &mut EditView| {
+                                view.get_content()
+                            }).unwrap();
                         find(s, &text);
                     })
                     .dismiss_button("Cancel"),

examples/theme.rs

@@ -1,12 +1,13 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::views::{Dialog, TextView};
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();
     // You can load a theme from a file at runtime for fast development.
-    siv.load_theme_file("assets/style.toml").unwrap();
+    siv.load_theme_file("assets/style.toml")
+        .unwrap();
 
     // Or you can directly load it from a string for easy deployment.
     // siv.load_theme(include_str!("../assets/style.toml")).unwrap();

examples/theme_manual.rs

@@ -1,14 +1,16 @@
 extern crate cursive;
 
-use cursive::Cursive;
 use cursive::theme::{BaseColor, BorderStyle, Color, ColorStyle};
 use cursive::views::{Dialog, EditView, LinearLayout, TextView};
+use cursive::Cursive;
 
 fn main() {
     let mut siv = Cursive::default();
 
     let layout = LinearLayout::vertical()
-        .child(TextView::new("This is a dynamic theme example!"))
+        .child(TextView::new(
+            "This is a dynamic theme example!",
+        ))
         .child(EditView::new().content("Woo! colors!").style(
             ColorStyle::new(
                 Color::Rgb(200, 150, 150),

examples/vpv.rs

@@ -3,10 +3,10 @@ extern crate pretty_bytes;
 
 use std::io;
 
-use cursive::Cursive;
 use cursive::traits::{Boxable, With};
 use cursive::utils;
 use cursive::views::{Canvas, Dialog, LinearLayout, ProgressBar};
+use cursive::Cursive;
 use pretty_bytes::converter::convert;
 use std::thread;
 use std::time;
@@ -31,10 +31,7 @@ fn main() {
             let meta = std::fs::metadata(&source).unwrap();
             // If possible, read the file size to have a progress bar.
             let len = meta.len();
-            (
-                Some(source),
-                if len > 0 { Some(len) } else { None },
-            )
+            (Some(source), if len > 0 { Some(len) } else { None })
         }
         None => (None, None),
     };

src/align.rs

@@ -12,7 +12,7 @@ pub struct Align {
 impl Align {
     /// Creates a new Align object from the given alignments.
     pub fn new(h: HAlign, v: VAlign) -> Self {
-        Align { h: h, v: v }
+        Align { h, v }
     }
 
     /// Creates a top-left alignment.

src/backend/blt.rs

@@ -5,10 +5,11 @@
 
 extern crate bear_lib_terminal;
 
-use self::bear_lib_terminal::Color as BltColor;
 use self::bear_lib_terminal::geometry::Size;
-use self::bear_lib_terminal::terminal::{self, state, Event as BltEvent,
-                                        KeyCode};
+use self::bear_lib_terminal::terminal::{
+    self, state, Event as BltEvent, KeyCode,
+};
+use self::bear_lib_terminal::Color as BltColor;
 use backend;
 use event::{Event, Key, MouseButton, MouseEvent};
 use std::collections::HashSet;
@@ -108,7 +109,7 @@ impl Backend {
     }
 
     fn blt_keycode_to_ev(
-        &mut self, kc: KeyCode, shift: bool, ctrl: bool
+        &mut self, kc: KeyCode, shift: bool, ctrl: bool,
     ) -> Event {
         match kc {
             KeyCode::F1
@@ -238,7 +239,7 @@ impl backend::Backend for Backend {
     fn set_color(&self, color: ColorPair) -> ColorPair {
         let current = ColorPair {
             front: blt_colour_to_colour(state::foreground()),
-            back:  blt_colour_to_colour(state::background())
+            back: blt_colour_to_colour(state::background()),
         };
 
         let fg = colour_to_blt_colour(color.front, ColorRole::Foreground);
@@ -255,14 +256,14 @@ impl backend::Backend for Backend {
             Effect::Bold
             | Effect::Italic
             | Effect::Underline
-            | Effect::Simple => {},
+            | Effect::Simple => {}
             // TODO: how to do this correctly?`
             //       BLT itself doesn't do this kind of thing,
             //       we'd need the colours in our position,
             //       but `f()` can do whatever
-            Effect::Reverse => terminal::set_colors(
-                state::background(), state::foreground()
-            ),
+            Effect::Reverse => {
+                terminal::set_colors(state::background(), state::foreground())
+            }
         }
     }
 
@@ -272,11 +273,11 @@ impl backend::Backend for Backend {
             Effect::Bold
             | Effect::Italic
             | Effect::Underline
-            | Effect::Simple => {},
+            | Effect::Simple => {}
             // The process of reversing is the same as unreversing
-            Effect::Reverse => terminal::set_colors(
-                state::background(), state::foreground()
-            ),
+            Effect::Reverse => {
+                terminal::set_colors(state::background(), state::foreground())
+            }
         }
     }
 

src/backend/curses/mod.rs

@@ -63,7 +63,7 @@ where
 
 fn find_closest_pair(pair: &ColorPair, max_colors: i16) -> (i16, i16) {
     (
-        find_closest(&pair.front,max_colors),
+        find_closest(&pair.front, max_colors),
         find_closest(&pair.back, max_colors),
     )
 }
@@ -95,7 +95,7 @@ fn find_closest(color: &Color, max_colors: i16) -> i16 {
                 // (r - 8) / 10 = n
                 //
                 let n = (r - 8) / 10;
-                (232 + n) as i16
+                i16::from(232 + n)
             } else {
                 // Generic RGB
                 let r = 6 * u16::from(r) / 256;

src/backend/curses/n.rs

@@ -1,7 +1,7 @@
 extern crate ncurses;
 
-use self::ncurses::mmask_t;
 use self::super::split_i32;
+use self::ncurses::mmask_t;
 use backend;
 use event::{Event, Key, MouseButton, MouseEvent};
 use theme::{Color, ColorPair, Effect};
@@ -206,10 +206,9 @@ impl Backend {
         Box::new(c)
     }
 
-
     /// Save a new color pair.
     fn insert_color(
-        &self, pairs: &mut HashMap<(i16, i16), i16>, (front, back): (i16, i16)
+        &self, pairs: &mut HashMap<(i16, i16), i16>, (front, back): (i16, i16),
     ) -> i16 {
         let n = 1 + pairs.len() as i16;
 
@@ -250,7 +249,6 @@ impl Backend {
         ncurses::attron(style);
     }
 
-
 }
 
 impl backend::Backend for Backend {

src/backend/curses/pan.rs

@@ -1,7 +1,7 @@
 extern crate pancurses;
 
-use self::pancurses::mmask_t;
 use self::super::split_i32;
+use self::pancurses::mmask_t;
 use backend;
 use event::{Event, Key, MouseButton, MouseEvent};
 use std::cell::{Cell, RefCell};
@@ -307,9 +307,7 @@ impl Backend {
 
     /// Save a new color pair.
     fn insert_color(
-        &self,
-        pairs: &mut HashMap<(i16,i16), i32>,
-        (front, back): (i16, i16),
+        &self, pairs: &mut HashMap<(i16, i16), i32>, (front, back): (i16, i16),
     ) -> i32 {
         let n = 1 + pairs.len() as i32;
 
@@ -351,6 +349,68 @@ impl Backend {
         self.window.attron(style);
     }
 
+<<<<<<< HEAD
+=======
+    fn parse_mouse_event(&mut self) -> Event {
+        let mut mevent = match pancurses::getmouse() {
+            Err(code) => return Event::Unknown(split_i32(code)),
+            Ok(event) => event,
+        };
+
+        let _shift = (mevent.bstate & pancurses::BUTTON_SHIFT as mmask_t) != 0;
+        let _alt = (mevent.bstate & pancurses::BUTTON_ALT as mmask_t) != 0;
+        let _ctrl = (mevent.bstate & pancurses::BUTTON_CTRL as mmask_t) != 0;
+
+        mevent.bstate &= !(pancurses::BUTTON_SHIFT
+            | pancurses::BUTTON_ALT
+            | pancurses::BUTTON_CTRL) as mmask_t;
+
+        let make_event = |event| Event::Mouse {
+            offset: Vec2::zero(),
+            position: Vec2::new(mevent.x as usize, mevent.y as usize),
+            event: event,
+        };
+
+        if mevent.bstate == pancurses::REPORT_MOUSE_POSITION as mmask_t {
+            // The event is either a mouse drag event,
+            // or a weird double-release event. :S
+            self.last_mouse_button
+                .map(MouseEvent::Hold)
+                .map(&make_event)
+                .unwrap_or_else(|| {
+                    debug!("We got a mouse drag, but no last mouse pressed?");
+                    Event::Unknown(vec![])
+                })
+        } else {
+            // Identify the button
+            let mut bare_event = mevent.bstate & ((1 << 25) - 1);
+
+            let mut event = None;
+            while bare_event != 0 {
+                let single_event = 1 << bare_event.trailing_zeros();
+                bare_event ^= single_event;
+
+                // Process single_event
+                on_mouse_event(single_event, |e| {
+                    if event.is_none() {
+                        event = Some(e);
+                    } else {
+                        self.event_queue.push(make_event(e));
+                    }
+                });
+            }
+            if let Some(event) = event {
+                if let Some(btn) = event.button() {
+                    self.last_mouse_button = Some(btn);
+                }
+                make_event(event)
+            } else {
+                debug!("No event parsed?...");
+                Event::Unknown(vec![])
+            }
+        }
+    }
+>>>>>>> master
 }
 
 impl backend::Backend for Backend {

src/backend/dummy.rs

@@ -1,7 +1,7 @@
 //! Dummy backend
 use backend;
-use theme;
 use event;
+use theme;
 use vec::Vec2;
 
 use std::time::Duration;

src/backend/mod.rs

@@ -18,9 +18,9 @@ use std::time::Duration;
 
 pub mod dummy;
 
-pub mod termion;
 pub mod blt;
 pub mod curses;
+pub mod termion;
 
 /// Trait defining the required methods to be a backend.
 pub trait Backend {
@@ -72,7 +72,6 @@ pub trait Backend {
     /// Enables the given effect.
     fn set_effect(&self, effect: theme::Effect);
 
-
     /// Disables the given effect.
     fn unset_effect(&self, effect: theme::Effect);
 }

src/cursive.rs

@@ -133,7 +133,7 @@ impl Cursive {
 
         Cursive {
             fps: 0,
-            theme: theme,
+            theme,
             screens: vec![views::StackView::new()],
             last_sizes: Vec::new(),
             global_callbacks: HashMap::new(),
@@ -309,8 +309,8 @@ impl Cursive {
     /// Loads a theme from the given string content.
     ///
     /// Content must be valid toml.
-    pub fn load_theme(&mut self, content: &str) -> Result<(), theme::Error> {
-        self.set_theme(try!(theme::load_theme(content)));
+    pub fn load_toml(&mut self, content: &str) -> Result<(), theme::Error> {
+        self.set_theme(try!(theme::load_toml(content)));
         Ok(())
     }
 
@@ -649,7 +649,7 @@ impl Cursive {
         // Print the stackview background before the menubar
         let offset = if self.menubar.autohide { 0 } else { 1 };
         let id = self.active_screen;
-        let sv_printer = printer.offset((0, offset), !selected);
+        let sv_printer = printer.offset((0, offset)).focused(!selected);
 
         self.screens[id].draw_bg(&sv_printer);
 
@@ -657,11 +657,7 @@ impl Cursive {
         // If the menubar is active, nothing else can be.
         // Draw the menubar?
         if self.menubar.visible() {
-            let printer = printer.sub_printer(
-                Vec2::zero(),
-                printer.size,
-                self.menubar.receive_events(),
-            );
+            let printer = printer.focused(self.menubar.receive_events());
             self.menubar.draw(&printer);
         }
 

src/direction.rs

@@ -15,8 +15,8 @@
 //! * Relative direction: front or back.
 //!   Its actual direction depends on the orientation.
 
-use XY;
 use vec::Vec2;
+use XY;
 
 /// Describes a vertical or horizontal orientation for a view.
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -28,6 +28,11 @@ pub enum Orientation {
 }
 
 impl Orientation {
+    /// Returns a `XY(Horizontal, Vertical)`.
+    pub fn pair() -> XY<Orientation> {
+        XY::new(Orientation::Horizontal, Orientation::Vertical)
+    }
+
     /// Returns the component of `v` corresponding to this orientation.
     ///
     /// (`Horizontal` will return the x value,

src/event.rs

@@ -13,10 +13,11 @@
 //!   [global callback](../struct.Cursive.html#method.add_global_callback)
 //!   table is checked.
 
-use Cursive;
+use std::any::Any;
 use std::ops::Deref;
 use std::rc::Rc;
 use vec::Vec2;
+use Cursive;
 
 /// Callback is a function that can be triggered by an event.
 /// It has a mutable access to the cursive root.
@@ -24,6 +25,9 @@ use vec::Vec2;
 pub struct Callback(Rc<Box<Fn(&mut Cursive)>>);
 // TODO: remove the Box when Box<T: Sized> -> Rc<T> is possible
 
+/// A boxed callback that can be run on `&mut Any`.
+pub type AnyCb<'a> = Box<FnMut(&mut Any) + 'a>;
+
 impl Callback {
     /// Wraps the given function into a `Callback` object.
     pub fn from_fn<F>(f: F) -> Self
@@ -343,6 +347,20 @@ impl Event {
         }
     }
 
+    /// Returns a mutable reference to the position of the mouse/
+    ///
+    /// Returns `None` if `self` is not a mouse event.
+    pub fn mouse_position_mut(&mut self) -> Option<&mut Vec2> {
+        if let Event::Mouse {
+            ref mut position, ..
+        } = *self
+        {
+            Some(position)
+        } else {
+            None
+        }
+    }
+
     /// Update `self` with the given offset.
     ///
     /// If `self` is a mouse event, adds `top_left` to its offset.

src/lib.rs

@@ -74,8 +74,8 @@ extern crate chan;
 #[macro_use]
 extern crate maplit;
 
-extern crate num;
 extern crate libc;
+extern crate num;
 extern crate owning_ref;
 extern crate toml;
 extern crate unicode_segmentation;
@@ -98,20 +98,20 @@ pub mod event;
 #[macro_use]
 pub mod view;
 
-pub mod views;
-pub mod vec;
+pub mod align;
+pub mod direction;
+pub mod menu;
 pub mod rect;
 pub mod theme;
-pub mod align;
-pub mod menu;
-pub mod direction;
 pub mod utils;
+pub mod vec;
+pub mod views;
 
 // This probably doesn't need to be public?
 mod cursive;
 mod printer;
-mod xy;
 mod with;
+mod xy;
 
 mod div;
 mod utf8;

src/menu.rs

@@ -12,10 +12,10 @@
 //!
 //! [menubar]: ../struct.Cursive.html#method.menubar
 
-use Cursive;
-use With;
 use event::Callback;
 use std::rc::Rc;
+use Cursive;
+use With;
 
 /// Root of a menu tree.
 #[derive(Default, Clone)]

src/printer.rs

@@ -1,46 +1,84 @@
-//! Makes drawing on ncurses windows easier.
+//! Provide higher-level abstraction to draw things on backends.
 
 use backend::Backend;
+use direction::Orientation;
 use enumset::EnumSet;
-use std::cell::Cell;
 use std::cmp::min;
-use std::rc::Rc;
 use theme::{BorderStyle, ColorStyle, Effect, PaletteColor, Style, Theme};
 use unicode_segmentation::UnicodeSegmentation;
-use utils::lines::simple::prefix;
+use unicode_width::UnicodeWidthStr;
+use utils::lines::simple::{prefix, suffix};
 use vec::Vec2;
+use with::With;
 
 /// Convenient interface to draw on a subset of the screen.
-pub struct Printer<'a> {
+///
+/// The area it can print on is defined by `offset` and `size`.
+///
+/// The part of the content it will print is defined by `content_offset`
+/// and `size`.
+pub struct Printer<'a, 'b> {
     /// Offset into the window this printer should start drawing at.
+    ///
+    /// A print request at `x` will really print at `x + offset`.
     pub offset: Vec2,
+
     /// Size of the area we are allowed to draw on.
+    ///
+    /// Anything outside of this should be discarded.
+    pub output_size: Vec2,
+
+    /// Size allocated to the view.
+    ///
+    /// This should be the same value as the one given in the last call to
+    /// `View::layout`.
     pub size: Vec2,
+
+    /// Offset into the view for this printer.
+    ///
+    /// A print request `x`, will really print at `x - content_offset`.
+    pub content_offset: Vec2,
+
     /// Whether the view to draw is currently focused or not.
     pub focused: bool,
+
     /// Currently used theme
     pub theme: &'a Theme,
 
-    /// `true` if nothing has been drawn yet.
-    new: Rc<Cell<bool>>,
     /// Backend used to actually draw things
-    backend: &'a Backend,
+    backend: &'b Backend,
 }
 
-impl<'a> Printer<'a> {
+impl<'a, 'b> Clone for Printer<'a, 'b> {
+    fn clone(&self) -> Self {
+        Printer {
+            offset: self.offset,
+            content_offset: self.content_offset,
+            output_size: self.output_size,
+            size: self.size,
+            focused: self.focused,
+            theme: self.theme,
+            backend: self.backend,
+        }
+    }
+}
+
+impl<'a, 'b> Printer<'a, 'b> {
     /// Creates a new printer on the given window.
     ///
     /// But nobody needs to know that.
     #[doc(hidden)]
     pub fn new<T: Into<Vec2>>(
-        size: T, theme: &'a Theme, backend: &'a Backend
+        size: T, theme: &'a Theme, backend: &'b Backend,
     ) -> Self {
+        let size = size.into();
         Printer {
             offset: Vec2::zero(),
-            size: size.into(),
+            content_offset: Vec2::zero(),
+            output_size: size,
+            size,
             focused: true,
             theme,
-            new: Rc::new(Cell::new(true)),
             backend,
         }
     }
@@ -55,61 +93,152 @@ impl<'a> Printer<'a> {
             .clear(self.theme.palette[PaletteColor::Background]);
     }
 
-    /// Returns `true` if nothing has been printed yet.
-    pub fn is_new(&self) -> bool {
-        self.new.get()
-    }
-
     // TODO: use &mut self? We don't *need* it, but it may make sense.
     // We don't want people to start calling prints in parallel?
     /// Prints some text at the given position relative to the window.
-    pub fn print<S: Into<Vec2>>(&self, pos: S, text: &str) {
-        self.new.set(false);
+    pub fn print<S: Into<Vec2>>(&self, start: S, text: &str) {
+        // Where we are asked to start printing. Oh boy.
+        let start = start.into();
 
-        let p = pos.into();
-        if p.y >= self.size.y || p.x >= self.size.x {
+        // We accept requests between `content_offset` and
+        // `content_offset + output_size`.
+        if !(start < (self.output_size + self.content_offset)) {
             return;
         }
+
+        // If start < content_offset, part of the text will not be visible.
+        // This is the part of the text that's hidden:
+        // (It should always be smaller than the content offset)
+        let hidden_part = self.content_offset.saturating_sub(start);
+        if hidden_part.y > 0 {
+            // Since we are printing a single line, there's nothing we can do.
+            return;
+        }
+
+        let text_width = text.width();
+
+        // If we're waaaay too far left, just give up.
+        if hidden_part.x > text_width {
+            return;
+        }
+
+        // We have to drop hidden_part.x width from the start of the string.
+        // prefix() may be too short if there's a double-width character.
+        // So instead, keep the suffix and drop the prefix.
+
+        // TODO: use a different prefix method that is *at least* the width
+        // (and not *at most*)
+        let tail =
+            suffix(text.graphemes(true), text_width - hidden_part.x, "");
+        let skipped_len = text.len() - tail.length;
+        let skipped_width = text_width - tail.width;
+        assert_eq!(text[..skipped_len].width(), skipped_width);
+
+        // This should be equal most of the time, except when there's a double
+        // character preventing us from splitting perfectly.
+        assert!(skipped_width >= hidden_part.x);
+
+        // Drop part of the text, and move the cursor correspondingly.
+        let text = &text[skipped_len..];
+        let start = start + (skipped_width, 0);
+        assert!(start.fits(self.content_offset));
+
+        // What we did before should guarantee that this won't overflow.
+        let start = start - self.content_offset;
+
         // Do we have enough room for the entire line?
-        let room = self.size.x - p.x;
+        let room = self.output_size.x - start.x;
+
+        // Drop the end of the text if it's too long
         // We want the number of CHARACTERS, not bytes.
         // (Actually we want the "width" of the string, see unicode-width)
         let prefix_len = prefix(text.graphemes(true), room, "").length;
         let text = &text[..prefix_len];
+        assert!(text.width() <= room);
 
-        let p = p + self.offset;
-        self.backend.print_at(p, text);
+        let start = start + self.offset;
+        self.backend.print_at(start, text);
     }
 
     /// Prints a vertical line using the given character.
-    pub fn print_vline<T: Into<Vec2>>(&self, start: T, len: usize, c: &str) {
-        self.new.set(false);
+    pub fn print_vline<T: Into<Vec2>>(
+        &self, start: T, height: usize, c: &str,
+    ) {
+        let start = start.into();
 
-        let p = start.into();
-        if p.y > self.size.y || p.x > self.size.x {
+        // Here again, we can abort if we're trying to print too far right or
+        // too low.
+        if !start.fits_in(self.output_size + self.content_offset) {
             return;
         }
-        let len = min(len, self.size.y - p.y);
 
-        let p = p + self.offset;
-        for y in 0..len {
-            self.backend.print_at(p + (0,y), c);
+        // hidden_part describes how far to the top left of the viewport we are.
+        let hidden_part = self.content_offset.saturating_sub(start);
+        if hidden_part.x > 0 || hidden_part.y >= height {
+            // We're printing a single column, so we can't do much here.
+            return;
+        }
+
+        // Skip `hidden_part`
+        let start = start + hidden_part;
+        assert!(start.fits(self.content_offset));
+
+        let height = height - hidden_part.y;
+
+        // What we did before ensures this won't overflow.
+        let start = start - self.content_offset;
+
+        // Don't go overboard
+        let height = min(height, self.output_size.y - start.y);
+
+        let start = start + self.offset;
+        for y in 0..height {
+            self.backend.print_at(start + (0, y), c);
+        }
+    }
+
+    /// Prints a line using the given character.
+    pub fn print_line<T: Into<Vec2>>(
+        &self, orientation: Orientation, start: T, length: usize, c: &str,
+    ) {
+        match orientation {
+            Orientation::Vertical => self.print_vline(start, length, c),
+            Orientation::Horizontal => self.print_hline(start, length, c),
         }
     }
 
     /// Prints a horizontal line using the given character.
-    pub fn print_hline<T: Into<Vec2>>(&self, start: T, len: usize, c: &str) {
-        self.new.set(false);
+    pub fn print_hline<T: Into<Vec2>>(&self, start: T, width: usize, c: &str) {
+        let start = start.into();
 
-        let p = start.into();
-        if p.y > self.size.y || p.x > self.size.x {
+        // Nothing to be done if the start if too far to the bottom/right
+        if !start.fits_in(self.output_size + self.content_offset) {
             return;
         }
-        let len = min(len, self.size.x - p.x);
-        let text: String = ::std::iter::repeat(c).take(len).collect();
 
-        let p = p + self.offset;
-        self.backend.print_at(p, &text);
+        let hidden_part = self.content_offset.saturating_sub(start);
+        if hidden_part.y > 0 || hidden_part.x >= width {
+            // We're printing a single line, so we can't do much here.
+            return;
+        }
+
+        // Skip `hidden_part`
+        let start = start + hidden_part;
+        assert!(start.fits(self.content_offset));
+
+        let width = width - hidden_part.x;
+
+        // Don't go too far
+        let start = start - self.content_offset;
+
+        // Don't write too much if we're close to the end
+        let width = min(width, (self.output_size.x - start.x) / c.width());
+
+        // Could we avoid allocating?
+        let text: String = ::std::iter::repeat(c).take(width).collect();
+
+        let start = start + self.offset;
+        self.backend.print_at(start, &text);
     }
 
     /// Call the given closure with a colored printer,
@@ -149,8 +278,6 @@ impl<'a> Printer<'a> {
         let color = style.color;
         let effects = style.effects;
 
-        // eprintln!("{:?}", effects);
-
         if let Some(color) = color {
             self.with_color(color, |printer| {
                 printer.with_effects(effects, f);
@@ -171,6 +298,24 @@ impl<'a> Printer<'a> {
         self.backend.unset_effect(effect);
     }
 
+    /// Call the given closure with a modified printer
+    /// that will apply the given theme on prints.
+    pub fn with_theme<F>(&self, theme: &Theme, f: F)
+    where
+        F: FnOnce(&Printer),
+    {
+        let new_printer = Printer {
+            offset: self.offset,
+            size: self.size,
+            focused: self.focused,
+            theme: theme,
+            backend: self.backend,
+            output_size: self.output_size,
+            content_offset: self.content_offset,
+        };
+        f(&new_printer);
+    }
+
     /// Call the given closure with a modified printer
     /// that will apply each given effect on prints.
     pub fn with_effects<F>(&self, effects: EnumSet<Effect>, f: F)
@@ -205,10 +350,8 @@ impl<'a> Printer<'a> {
     /// printer.print_box((0,0), (6,4), false);
     /// ```
     pub fn print_box<T: Into<Vec2>, S: Into<Vec2>>(
-        &self, start: T, size: S, invert: bool
+        &self, start: T, size: S, invert: bool,
     ) {
-        self.new.set(false);
-
         let start = start.into();
         let size = size.into();
 
@@ -293,37 +436,98 @@ impl<'a> Printer<'a> {
     }
 
     /// Prints a horizontal delimiter with side border `├` and `┤`.
-    pub fn print_hdelim<T: Into<Vec2>>(&self, start: T, len: usize) {
+    pub fn print_hdelim<T>(&self, start: T, len: usize)
+    where
+        T: Into<Vec2>,
+    {
         let start = start.into();
         self.print(start, "├");
         self.print_hline(start + (1, 0), len.saturating_sub(2), "─");
         self.print(start + (len.saturating_sub(1), 0), "┤");
     }
 
-    /// Returns a printer on a subset of this one's area.
-    pub fn sub_printer<S: Into<Vec2>, T: Into<Vec2>>(
-        &'a self, offset: S, size: T, focused: bool
-    ) -> Printer<'a> {
-        let size = size.into();
-        let offset = offset.into().or_min(self.size);
-        let available = if !offset.fits_in(self.size) {
-            Vec2::zero()
-        } else {
-            Vec2::min(self.size - offset, size)
-        };
-        Printer {
-            offset: self.offset + offset,
-            // We can't be larger than what remains
-            size: available,
-            focused: self.focused && focused,
-            theme: self.theme,
-            backend: self.backend,
-            new: Rc::clone(&self.new),
-        }
+    /// Returns a sub-printer with the given offset.
+    ///
+    /// It will print in an area slightly to the bottom/right.
+    pub fn offset<S>(&self, offset: S) -> Printer
+    where
+        S: Into<Vec2>,
+    {
+        let offset = offset.into();
+        self.clone().with(|s| {
+            // If we are drawing a part of the content,
+            // let's reduce this first.
+            let consumed = Vec2::min(s.content_offset, offset);
+
+            let offset = offset - consumed;
+            s.content_offset = s.content_offset - consumed;
+
+            s.offset = s.offset + offset;
+
+            s.output_size = s.output_size.saturating_sub(offset);
+            s.size = s.size.saturating_sub(offset);
+        })
     }
 
-    /// Returns a sub-printer with the given offset.
-    pub fn offset<S: Into<Vec2>>(&self, offset: S, focused: bool) -> Printer {
-        self.sub_printer(offset, self.size, focused)
+    /// Returns a new sub-printer inheriting the given focus.
+    ///
+    /// If `self` is focused and `focused == true`, the child will be focused.
+    ///
+    /// Otherwise, he will be unfocused.
+    pub fn focused(&self, focused: bool) -> Self {
+        self.clone().with(|s| {
+            s.focused &= focused;
+        })
+    }
+
+    /// Returns a new sub-printer with a cropped area.
+    ///
+    /// The new printer size will be the minimum of `size` and its current size.
+    ///
+    /// Any size reduction happens at the bottom-right.
+    pub fn cropped<S>(&self, size: S) -> Self
+    where
+        S: Into<Vec2>,
+    {
+        self.clone().with(|s| {
+            let size = size.into();
+            s.output_size = Vec2::min(s.output_size, size);
+            s.size = Vec2::min(s.size, size);
+        })
+    }
+
+    /// Returns a new sub-printer with a shrinked area.
+    ///
+    /// The printer size will be reduced by the given border from the bottom-right.
+    pub fn shrinked<S>(&self, borders: S) -> Self
+    where
+        S: Into<Vec2>,
+    {
+        self.cropped(self.size.saturating_sub(borders))
+    }
+
+    /// Returns a new sub-printer with a content offset.
+    pub fn content_offset<S>(&self, offset: S) -> Self
+    where
+        S: Into<Vec2>,
+    {
+        self.clone().with(|s| {
+            s.content_offset = s.content_offset + offset;
+        })
+    }
+
+    /// Returns a sub-printer with a different inner size.
+    ///
+    /// This will not change the actual output size, but will appear bigger to
+    /// users of this printer.
+    ///
+    /// Useful to give to children who think they're big, but really aren't.
+    pub fn inner_size<S>(&self, size: S) -> Self
+    where
+        S: Into<Vec2>,
+    {
+        self.clone().with(|s| {
+            s.size = size.into();
+        })
     }
 }

src/rect.rs

@@ -1,5 +1,5 @@
 //! Rectangles on the 2D character grid.
-
+use std::ops::Add;
 use vec::Vec2;
 
 /// A non-empty rectangle on the 2D grid.
@@ -7,7 +7,9 @@ use vec::Vec2;
 ///
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Rect {
+    /// Top-left corner, inclusive
     top_left: Vec2,
+    /// Bottom-right corner, inclusive
     bottom_right: Vec2,
 }
 
@@ -21,6 +23,18 @@ where
     }
 }
 
+impl<T> Add<T> for Rect
+where
+    T: Into<Vec2>,
+{
+    type Output = Rect;
+
+    fn add(mut self, rhs: T) -> Self {
+        self.offset(rhs);
+        self
+    }
+}
+
 impl Rect {
     /// Creates a new `Rect` with the given position and size.
     ///
@@ -80,7 +94,10 @@ impl Rect {
     }
 
     /// Adds the given offset to this rectangle.
-    pub fn offset<V>(&mut self, offset: V) where V: Into<Vec2> {
+    pub fn offset<V>(&mut self, offset: V)
+    where
+        V: Into<Vec2>,
+    {
         let offset = offset.into();
         self.top_left = self.top_left + offset;
         self.bottom_right = self.bottom_right + offset;
@@ -122,21 +139,29 @@ impl Rect {
     }
 
     /// Returns the Y value of the top edge of the rectangle.
+    ///
+    /// This is inclusive.
     pub fn top(self) -> usize {
         self.top_left.y
     }
 
     /// Returns the X value of the left edge of the rectangle.
+    ///
+    /// This is inclusive.
     pub fn left(self) -> usize {
         self.top_left.x
     }
 
     /// Returns the X value of the right edge of the rectangle.
+    ///
+    /// This is inclusive.
     pub fn right(self) -> usize {
         self.bottom_right.x
     }
 
     /// Returns the Y value of the botton edge of the rectangle.
+    ///
+    /// This is inclusive.
     pub fn bottom(self) -> usize {
         self.bottom_right.y
     }
@@ -145,4 +170,9 @@ impl Rect {
     pub fn surface(self) -> usize {
         self.width() * self.height()
     }
+
+    /// Checks if a point is in `self`.
+    pub fn contains(self, point: Vec2) -> bool {
+        point.fits(self.top_left) && point.fits_in(self.bottom_right)
+    }
 }

src/theme/color.rs

@@ -114,6 +114,13 @@ impl Color {
         }
     }
 
+    /// Parse a string into a color.
+    ///
+    /// Examples:
+    /// * `"red"` becomes `Color::Dark(BaseColor::Red)`
+    /// * `"light green"` becomes `Color::Light(BaseColor::Green)`
+    /// * `"default"` becomes `Color::TerminalDefault`
+    /// * `"#123456"` becomes `Color::Rgb(0x12, 0x34, 0x56)`
     pub(crate) fn parse(value: &str) -> Option<Self> {
         Some(match value {
             "black" => Color::Dark(BaseColor::Black),
@@ -149,11 +156,15 @@ impl Color {
             let r = load_hex(&value[0..l]) * multiplier;
             let g = load_hex(&value[l..2 * l]) * multiplier;
             let b = load_hex(&value[2 * l..3 * l]) * multiplier;
+
             Some(Color::Rgb(r as u8, g as u8, b as u8))
         } else if value.len() == 3 {
             // RGB values between 0 and 5 maybe?
+            // Like 050 for green
             let rgb: Vec<_> =
                 value.chars().map(|c| c as i16 - '0' as i16).collect();
+
+            assert_eq!(rgb.len(), 3);
             if rgb.iter().all(|&i| i >= 0 && i < 6) {
                 Some(Color::RgbLowRes(
                     rgb[0] as u8,

src/theme/mod.rs

@@ -156,20 +156,20 @@
 //! 	highlight          = "#F00"
 //! 	highlight_inactive = "#5555FF"
 //! ```
-mod style;
-mod effect;
+mod border_style;
 mod color;
 mod color_pair;
 mod color_style;
-mod border_style;
+mod effect;
 mod palette;
+mod style;
 
 pub use self::border_style::BorderStyle;
 pub use self::color::{BaseColor, Color};
 pub use self::color_pair::ColorPair;
 pub use self::color_style::{ColorStyle, ColorType};
 pub use self::effect::Effect;
-pub use self::palette::{default_palette, Palette, PaletteColor};
+pub use self::palette::{Palette, PaletteColor};
 pub use self::style::Style;
 use std::fs::File;
 use std::io;
@@ -193,13 +193,13 @@ impl Default for Theme {
         Theme {
             shadow: true,
             borders: BorderStyle::Simple,
-            palette: default_palette(),
+            palette: Palette::default(),
         }
     }
 }
 
 impl Theme {
-    fn load(&mut self, table: &toml::value::Table) {
+    fn load_toml(&mut self, table: &toml::value::Table) {
         if let Some(&toml::Value::Boolean(shadow)) = table.get("shadow") {
             self.shadow = shadow;
         }
@@ -209,7 +209,7 @@ impl Theme {
         }
 
         if let Some(&toml::Value::Table(ref table)) = table.get("colors") {
-            palette::load_table(&mut self.palette, table);
+            palette::load_toml(&mut self.palette, table);
         }
     }
 }
@@ -244,15 +244,15 @@ pub fn load_theme_file<P: AsRef<Path>>(filename: P) -> Result<Theme, Error> {
         content
     };
 
-    load_theme(&content)
+    load_toml(&content)
 }
 
 /// Loads a theme string and sets it as active.
-pub fn load_theme(content: &str) -> Result<Theme, Error> {
+pub fn load_toml(content: &str) -> Result<Theme, Error> {
     let table = toml::de::from_str(content)?;
 
     let mut theme = Theme::default();
-    theme.load(&table);
+    theme.load_toml(&table);
 
     Ok(theme)
 }

src/theme/palette.rs

@@ -2,6 +2,9 @@ use super::Color;
 use enum_map::EnumMap;
 use toml;
 
+use std::collections::HashMap;
+use std::ops::{Index, IndexMut};
+
 /// Color configuration for the application.
 ///
 /// Assign each color role an actual color.
@@ -11,17 +14,122 @@ use toml;
 /// # Example
 ///
 /// ```rust
-/// # use cursive::theme;
+/// # use cursive::theme::Palette;
 /// use cursive::theme::PaletteColor::*;
 /// use cursive::theme::Color::*;
 /// use cursive::theme::BaseColor::*;
 ///
-/// let mut palette = theme::default_palette();
+/// let mut palette = Palette::default();
 ///
 /// assert_eq!(palette[Background], Dark(Blue));
 /// palette[Shadow] = Light(Red);
 /// ```
-pub type Palette = EnumMap<PaletteColor, Color>;
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct Palette {
+    basic: EnumMap<PaletteColor, Color>,
+    custom: HashMap<String, PaletteNode>,
+}
+
+/// A node in the palette tree.
+///
+/// This describes a value attached to a custom keyword in the palette.
+///
+/// This can either be a color, or a nested namespace with its own mapping.
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub enum PaletteNode {
+    /// A single color.
+    Color(Color),
+    /// A group of values bundled in the same namespace.
+    ///
+    /// Namespaces can be merged in the palette with `Palette::merge`.
+    Namespace(HashMap<String, PaletteNode>),
+}
+
+// Basic usage: only use basic colors
+impl Index<PaletteColor> for Palette {
+    type Output = Color;
+
+    fn index(&self, palette_color: PaletteColor) -> &Color {
+        &self.basic[palette_color]
+    }
+}
+
+// We can alter existing color if needed (but why?...)
+impl IndexMut<PaletteColor> for Palette {
+    fn index_mut(&mut self, palette_color: PaletteColor) -> &mut Color {
+        &mut self.basic[palette_color]
+    }
+}
+
+impl Palette {
+    /// Returns a custom color from this palette.
+    ///
+    /// Returns `None` if the given key was not found.
+    pub fn custom<'a>(&'a self, key: &str) -> Option<&'a Color> {
+        self.custom.get(key).and_then(|node| {
+            if let &PaletteNode::Color(ref color) = node {
+                Some(color)
+            } else {
+                None
+            }
+        })
+    }
+
+    /// Returns a new palette where the given namespace has been merged.
+    ///
+    /// All values in the namespace will override previous values.
+    pub fn merge(&self, namespace: &str) -> Palette {
+        let mut result = self.clone();
+
+        if let Some(&PaletteNode::Namespace(ref palette)) =
+            self.custom.get(namespace)
+        {
+            // Merge `result` and `palette`
+            for (key, value) in palette.iter() {
+                match *value {
+                    PaletteNode::Color(color) => result.set_color(key, color),
+                    PaletteNode::Namespace(ref map) => {
+                        result.add_namespace(key, map.clone())
+                    }
+                }
+            }
+        }
+
+        result
+    }
+
+    /// Sets the color for the given key.
+    ///
+    /// This will update either the basic palette or the custom values.
+    pub fn set_color(&mut self, key: &str, color: Color) {
+        use theme::PaletteColor::*;
+
+        match key {
+            "background" => self.basic[Background] = color,
+            "shadow" => self.basic[Shadow] = color,
+            "view" => self.basic[View] = color,
+            "primary" => self.basic[Primary] = color,
+            "secondary" => self.basic[Secondary] = color,
+            "tertiary" => self.basic[Tertiary] = color,
+            "title_primary" => self.basic[TitlePrimary] = color,
+            "title_secondary" => self.basic[TitleSecondary] = color,
+            "highlight" => self.basic[Highlight] = color,
+            "highlight_inactive" => self.basic[HighlightInactive] = color,
+            other => {
+                self.custom
+                    .insert(other.to_string(), PaletteNode::Color(color));
+            }
+        }
+    }
+
+    /// Adds a color namespace to this palette.
+    pub fn add_namespace(
+        &mut self, key: &str, namespace: HashMap<String, PaletteNode>,
+    ) {
+        self.custom
+            .insert(key.to_string(), PaletteNode::Namespace(namespace));
+    }
+}
 
 /// Returns the default palette for a cursive application.
 ///
@@ -35,57 +143,84 @@ pub type Palette = EnumMap<PaletteColor, Color>;
 /// * `TitleSecondary` => `Dark(Yellow)`
 /// * `Highlight` => `Dark(Red)`
 /// * `HighlightInactive` => `Dark(Blue)`
-pub fn default_palette() -> Palette {
-    use self::PaletteColor::*;
-    use theme::BaseColor::*;
-    use theme::Color::*;
+impl Default for Palette {
+    fn default() -> Palette {
+        use self::PaletteColor::*;
+        use theme::BaseColor::*;
+        use theme::Color::*;
 
-    enum_map!{
-        Background => Dark(Blue),
-        Shadow => Dark(Black),
-        View => Dark(White),
-        Primary => Dark(Black),
-        Secondary => Dark(Blue),
-        Tertiary => Dark(White),
-        TitlePrimary => Dark(Red),
-        TitleSecondary => Dark(Yellow),
-        Highlight => Dark(Red),
-        HighlightInactive => Dark(Blue),
+        Palette {
+            basic: enum_map!{
+                Background => Dark(Blue),
+                Shadow => Dark(Black),
+                View => Dark(White),
+                Primary => Dark(Black),
+                Secondary => Dark(Blue),
+                Tertiary => Dark(White),
+                TitlePrimary => Dark(Red),
+                TitleSecondary => Dark(Yellow),
+                Highlight => Dark(Red),
+                HighlightInactive => Dark(Blue),
+            },
+            custom: HashMap::new(),
+        }
     }
 }
 
+// Iterate over a toml
+fn iterate_toml<'a>(
+    table: &'a toml::value::Table,
+) -> impl Iterator<Item = (&'a str, PaletteNode)> + 'a {
+    table.iter().flat_map(|(key, value)| {
+        let node = match value {
+            toml::Value::Table(table) => {
+                // This should define a new namespace
+                // Treat basic colors as simple string.
+                // We'll convert them back in the merge method.
+                let map = iterate_toml(table)
+                    .map(|(key, value)| (key.to_string(), value))
+                    .collect();
+                // Should we only return something if it's non-empty?
+                Some(PaletteNode::Namespace(map))
+            }
+            toml::Value::Array(colors) => {
+                // This should be a list of colors - just pick the first valid one.
+                colors
+                    .iter()
+                    .flat_map(toml::Value::as_str)
+                    .flat_map(Color::parse)
+                    .map(PaletteNode::Color)
+                    .next()
+            }
+            toml::Value::String(color) => {
+                // This describe a new color - easy!
+                Color::parse(color).map(PaletteNode::Color)
+            }
+            other => {
+                // Other - error?
+                debug!(
+                    "Found unexpected value in theme: {} = {:?}",
+                    key, other
+                );
+                None
+            }
+        };
+
+        node.map(|node| (key.as_str(), node))
+    })
+}
+
 /// Fills `palette` with the colors from the given `table`.
-pub(crate) fn load_table(palette: &mut Palette, table: &toml::value::Table) {
+pub(crate) fn load_toml(palette: &mut Palette, table: &toml::value::Table) {
     // TODO: use serde for that?
     // Problem: toml-rs doesn't do well with Enums...
-    load_color(
-        &mut palette[PaletteColor::Background],
-        table.get("background"),
-    );
-    load_color(&mut palette[PaletteColor::Shadow], table.get("shadow"));
-    load_color(&mut palette[PaletteColor::View], table.get("view"));
-    load_color(&mut palette[PaletteColor::Primary], table.get("primary"));
-    load_color(
-        &mut palette[PaletteColor::Secondary],
-        table.get("secondary"),
-    );
-    load_color(&mut palette[PaletteColor::Tertiary], table.get("tertiary"));
-    load_color(
-        &mut palette[PaletteColor::TitlePrimary],
-        table.get("title_primary"),
-    );
-    load_color(
-        &mut palette[PaletteColor::TitleSecondary],
-        table.get("title_secondary"),
-    );
-    load_color(
-        &mut palette[PaletteColor::Highlight],
-        table.get("highlight"),
-    );
-    load_color(
-        &mut palette[PaletteColor::HighlightInactive],
-        table.get("highlight_inactive"),
-    );
+
+    for (key, value) in iterate_toml(table) {
+        match value {
+            PaletteNode::Color(color) => palette.set_color(key, color),
+            PaletteNode::Namespace(map) => palette.add_namespace(key, map),
+        }
+    }
 }
 
 /// Color entry in a palette.
@@ -121,25 +256,3 @@ impl PaletteColor {
         palette[self]
     }
 }
-
-/// Parses `value` and fills `target` if it's a valid color.
-fn load_color(target: &mut Color, value: Option<&toml::Value>) -> bool {
-    if let Some(value) = value {
-        match *value {
-            toml::Value::String(ref value) => {
-                if let Some(color) = Color::parse(value) {
-                    *target = color;
-                    true
-                } else {
-                    false
-                }
-            }
-            toml::Value::Array(ref array) => {
-                array.iter().any(|item| load_color(target, Some(item)))
-            }
-            _ => false,
-        }
-    } else {
-        false
-    }
-}

src/traits.rs

@@ -8,7 +8,7 @@
 //! use cursive::traits::*;
 //! ```
 
-#[doc(no_inline)]
-pub use With;
 #[doc(no_inline)]
 pub use view::{Boxable, Finder, Identifiable, View};
+#[doc(no_inline)]
+pub use With;

src/utils/counter.rs

@@ -1,5 +1,5 @@
-use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
 
 /// Atomic counter used by [`ProgressBar`].
 ///

src/utils/lines/simple/lines_iterator.rs

@@ -70,10 +70,6 @@ impl<'a> Iterator for LinesIterator<'a> {
 
         let width = row.width;
 
-        Some(Row {
-            start,
-            end,
-            width,
-        })
+        Some(Row { start, end, width })
     }
 }

src/utils/lines/simple/mod.rs

@@ -61,18 +61,19 @@ where
     // `current_width` is the width of everything
     // before the next token, including any space.
     let mut current_width = 0;
-    let sum: usize = iter.take_while(|token| {
-        let width = token.width();
-        if current_width + width > available_width {
-            false
-        } else {
-            // Include the delimiter after this token.
-            current_width += width;
-            current_width += delimiter_width;
-            true
-        }
-    }).map(|token| token.len() + delimiter_len)
-        .sum();
+    let sum: usize =
+        iter.take_while(|token| {
+            let width = token.width();
+            if current_width + width > available_width {
+                false
+            } else {
+                // Include the delimiter after this token.
+                current_width += width;
+                current_width += delimiter_width;
+                true
+            }
+        }).map(|token| token.len() + delimiter_len)
+            .sum();
 
     // We counted delimiter once too many times,
     // but only if the iterator was non empty.
@@ -82,7 +83,7 @@ where
     debug_assert!(current_width <= available_width + delimiter_width);
 
     Span {
-        length: length,
+        length,
         width: current_width,
     }
 }

src/utils/lines/spans/chunk_iterator.rs

@@ -47,10 +47,7 @@ where
         }
 
         // Skip empty spans
-        if self.source.spans()[self.current_span]
-            .as_ref()
-            .is_empty()
-        {
+        if self.source.spans()[self.current_span].as_ref().is_empty() {
             self.current_span += 1;
             return self.next();
         }
@@ -123,13 +120,9 @@ where
                 self.current_span += 1;
 
                 // Skip empty spans
-                while let Some(true) = self.source
-                    .spans()
-                    .get(self.current_span)
-                    .map(|span| {
-                        span.as_ref()
-                            .resolve(self.source.source())
-                            .is_empty()
+                while let Some(true) =
+                    self.source.spans().get(self.current_span).map(|span| {
+                        span.as_ref().resolve(self.source.source()).is_empty()
                     }) {
                     self.current_span += 1;
                 }

src/utils/lines/spans/lines_iterator.rs

@@ -76,11 +76,8 @@ where
             self.width
         };
 
-        let mut chunks = prefix(
-            &mut self.iter,
-            allowed_width,
-            &mut self.chunk_offset,
-        );
+        let mut chunks =
+            prefix(&mut self.iter, allowed_width, &mut self.chunk_offset);
 
         // println!("Chunks..: {:?}", chunks);
 
@@ -152,10 +149,7 @@ where
 
         // We can know text was wrapped if the stop was optional,
         // and there's more coming.
-        let text_wrap = !chunks
-            .last()
-            .map(|c| c.hard_stop)
-            .unwrap_or(true)
+        let text_wrap = !chunks.last().map(|c| c.hard_stop).unwrap_or(true)
             && self.iter.peek().is_some();
 
         // If we had to break a line in two, then at least pretent we're
@@ -178,9 +172,6 @@ where
 
         // TODO: merge consecutive segments of the same span
 
-        Some(Row {
-            segments,
-            width,
-        })
+        Some(Row { segments, width })
     }
 }

src/utils/lines/spans/prefix.rs

@@ -3,7 +3,7 @@ use std::iter::Peekable;
 
 /// Concatenates chunks as long as they fit in the given width.
 pub fn prefix<I>(
-    tokens: &mut Peekable<I>, width: usize, offset: &mut ChunkPart
+    tokens: &mut Peekable<I>, width: usize, offset: &mut ChunkPart,
 ) -> Vec<Chunk>
 where
     I: Iterator<Item = Chunk>,

src/utils/lines/spans/tests.rs

@@ -8,9 +8,7 @@ fn input() -> StyledString {
     text.append(StyledString::styled("didn't", Effect::Bold));
     text.append(StyledString::plain(" say "));
     text.append(StyledString::styled("half", Effect::Italic));
-    text.append(StyledString::plain(
-        " the things people say I did.",
-    ));
+    text.append(StyledString::plain(" the things people say I did."));
     text.append(StyledString::plain("\n"));
     text.append(StyledString::plain("\n"));
     text.append(StyledString::plain("    - A. Einstein"));
@@ -49,25 +47,19 @@ fn test_line_breaks() {
                     attr: &Style::from(Effect::Italic),
                 },
             ],
-            vec![
-                Span {
-                    content: "the things people",
-                    attr: &Style::none(),
-                },
-            ],
-            vec![
-                Span {
-                    content: "say I did.",
-                    attr: &Style::none(),
-                },
-            ],
+            vec![Span {
+                content: "the things people",
+                attr: &Style::none(),
+            }],
+            vec![Span {
+                content: "say I did.",
+                attr: &Style::none(),
+            }],
             vec![],
-            vec![
-                Span {
-                    content: "    - A. Einstein",
-                    attr: &Style::none(),
-                },
-            ],
+            vec![Span {
+                content: "    - A. Einstein",
+                attr: &Style::none(),
+            }],
         ]
     );
 }

src/utils/markup/markdown.rs

@@ -73,10 +73,12 @@ impl<'a> Iterator for Parser<'a> {
                         self.stack.push(Style::from(Effect::Italic))
                     }
                     Tag::Header(level) => {
-                        return Some(self.literal(format!(
-                            "{} ",
-                            header(level as usize)
-                        )))
+                        return Some(
+                            self.literal(format!(
+                                "{} ",
+                                header(level as usize)
+                            )),
+                        )
                     }
                     Tag::Rule => return Some(self.literal("---")),
                     Tag::BlockQuote => return Some(self.literal("> ")),
@@ -139,10 +141,8 @@ Attention
 ====
 I *really* love __Cursive__!";
         let spans = parse_spans(input);
-        let spans: Vec<_> = spans
-            .iter()
-            .map(|span| span.resolve(input))
-            .collect();
+        let spans: Vec<_> =
+            spans.iter().map(|span| span.resolve(input)).collect();
 
         // println!("{:?}", spans);
         assert_eq!(

src/utils/reader.rs

@@ -18,10 +18,7 @@ impl<R: Read> ProgressReader<R> {
     /// You should make sure the progress bar knows how
     /// many bytes should be received.
     pub fn new(counter: Counter, reader: R) -> Self {
-        ProgressReader {
-            reader: reader,
-            counter: counter,
-        }
+        ProgressReader { reader, counter }
     }
 
     /// Unwraps this `ProgressReader`, returning the reader and counter.

src/utils/span.rs

@@ -195,15 +195,13 @@ impl<T> SpannedString<T> {
     {
         let source = source.into();
 
-        let spans = vec![
-            IndexedSpan {
-                content: IndexedCow::Borrowed {
-                    start: 0,
-                    end: source.len(),
-                },
-                attr,
+        let spans = vec![IndexedSpan {
+            content: IndexedCow::Borrowed {
+                start: 0,
+                end: source.len(),
             },
-        ];
+            attr,
+        }];
 
         Self::with_spans(source, spans)
     }

src/vec.rs

@@ -1,9 +1,9 @@
 //! Points on the 2D character grid.
 
-use XY;
 use num::traits::Zero;
 use std::cmp::{max, min, Ordering};
 use std::ops::{Add, Div, Mul, Sub};
+use XY;
 
 /// Simple 2D size, in cells.
 ///
@@ -240,6 +240,27 @@ impl Mul<usize> for XY<usize> {
     }
 }
 
+impl<T> Mul<XY<T>> for XY<T>
+where
+    T: Mul<T>,
+{
+    type Output = XY<T::Output>;
+
+    fn mul(self, other: XY<T>) -> Self::Output {
+        self.zip_map(other, |s, o| s * o)
+    }
+}
+impl<T> Div<XY<T>> for XY<T>
+where
+    T: Div<T>,
+{
+    type Output = XY<T::Output>;
+
+    fn div(self, other: XY<T>) -> Self::Output {
+        self.zip_map(other, |s, o| s / o)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::Vec2;

src/view/boxable.rs

@@ -8,7 +8,7 @@ use views::BoxView;
 pub trait Boxable: View + Sized {
     /// Wraps `self` in a `BoxView` with the given size constraints.
     fn boxed(
-        self, width: SizeConstraint, height: SizeConstraint
+        self, width: SizeConstraint, height: SizeConstraint,
     ) -> BoxView<Self> {
         BoxView::new(width, height, self)
     }

src/view/finder.rs

@@ -46,7 +46,8 @@ impl<T: View> Finder for T {
                         *result_ref =
                             v.downcast_mut::<V>().map(|v| callback(v));
                     } else if v.is::<IdView<V>>() {
-                        *result_ref = v.downcast_mut::<IdView<V>>()
+                        *result_ref = v
+                            .downcast_mut::<IdView<V>>()
                             .and_then(|v| v.with_view_mut(callback));
                     }
                 }

src/view/margins.rs

@@ -61,12 +61,7 @@ impl From<(usize, usize, usize, usize)> for Margins {
 
 impl From<(i32, i32, i32, i32)> for Margins {
     fn from((left, right, top, bottom): (i32, i32, i32, i32)) -> Margins {
-        (
-            left as usize,
-            right as usize,
-            top as usize,
-            bottom as usize,
-        ).into()
+        (left as usize, right as usize, top as usize, bottom as usize).into()
     }
 }
 

src/view/mod.rs

@@ -41,17 +41,17 @@ mod view_wrapper;
 // Essentials components
 mod any;
 mod finder;
-mod position;
 mod margins;
+mod position;
 mod size_cache;
 mod size_constraint;
-mod view_path;
 mod view;
+mod view_path;
 
 // Helper bases
-mod scroll;
-mod identifiable;
 mod boxable;
+mod identifiable;
+mod scroll;
 
 mod into_boxed_view;
 

src/view/position.rs

@@ -1,6 +1,6 @@
-use XY;
 use std::cmp::min;
 use vec::Vec2;
+use XY;
 
 /// Location of the view on screen
 pub type Position = XY<Offset>;
@@ -30,7 +30,7 @@ impl Position {
     /// child with its top-left corner at the returned coordinates will
     /// position him appropriately.
     pub fn compute_offset<S, A, P>(
-        &self, size: S, available: A, parent: P
+        &self, size: S, available: A, parent: P,
     ) -> Vec2
     where
         S: Into<Vec2>,
@@ -65,7 +65,7 @@ pub enum Offset {
 impl Offset {
     /// Computes a single-dimension offset requred to draw a view.
     pub fn compute_offset(
-        &self, size: usize, available: usize, parent: usize
+        &self, size: usize, available: usize, parent: usize,
     ) -> usize {
         if size > available {
             0

src/view/scroll.rs

@@ -1,8 +1,8 @@
-use Printer;
 use div::div_up;
 use std::cmp::{max, min};
 use theme::ColorStyle;
 use vec::Vec2;
+use Printer;
 
 /// Provide scrolling functionalities to a view.
 ///
@@ -262,7 +262,7 @@ impl ScrollBase {
             // Y is the actual coordinate of the line.
             // The item ID is then Y + self.start_line
             line_drawer(
-                &printer.sub_printer(Vec2::new(0, y), Vec2::new(w, 1), true),
+                &printer.offset((0, y)).cropped((w, 1)),
                 y + self.start_line,
             );
         }

src/view/size_cache.rs

@@ -18,10 +18,7 @@ pub struct SizeCache {
 impl SizeCache {
     /// Creates a new sized cache
     pub fn new(value: usize, constrained: bool) -> Self {
-        SizeCache {
-            value,
-            constrained,
-        }
+        SizeCache { value, constrained }
     }
 
     /// Returns `true` if `self` is still valid for the given `request`.

src/view/view.rs

@@ -1,15 +1,15 @@
-use Printer;
 use direction::Direction;
-use event::{Event, EventResult};
+use event::{AnyCb, Event, EventResult};
+use rect::Rect;
 use std::any::Any;
 use vec::Vec2;
 use view::{AnyView, Selector};
+use Printer;
 
 /// Main trait defining a view behaviour.
 ///
 /// This is what you should implement to define a custom View.
 pub trait View: Any + AnyView {
-
     /// Draws the view with the given printer (includes bounds) and focus.
     ///
     /// This is the only *required* method to implement.
@@ -63,7 +63,6 @@ pub trait View: Any + AnyView {
         EventResult::Ignored
     }
 
-
     /// Runs a closure on the view identified by the given selector.
     ///
     /// See [`Finder::call_on`] for a nicer interface, implemented for all
@@ -74,7 +73,7 @@ pub trait View: Any + AnyView {
     /// If the selector doesn't find a match, the closure will not be run.
     ///
     /// Default implementation is a no-op.
-    fn call_on_any<'a>(&mut self, _: &Selector, _: Box<FnMut(&mut Any) + 'a>) {
+    fn call_on_any<'a>(&mut self, _: &Selector, _: AnyCb<'a>) {
         // TODO: FnMut -> FnOnce once it works
     }
 
@@ -97,4 +96,16 @@ pub trait View: Any + AnyView {
         let _ = source;
         false
     }
+
+    /// What part of the view is important and should be visible?
+    ///
+    /// When only part of this view can be visible, this helps
+    /// determine which part.
+    ///
+    /// It is given the view size (same size given to `layout`).
+    ///
+    /// Default implementation return the entire view.
+    fn important_area(&self, view_size: Vec2) -> Rect {
+        Rect::from_corners((0, 0), view_size)
+    }
 }

src/view/view_wrapper.rs

@@ -1,9 +1,10 @@
-use Printer;
 use direction::Direction;
-use event::{Event, EventResult};
+use event::{AnyCb, Event, EventResult};
+use rect::Rect;
 use std::any::Any;
 use vec::Vec2;
 use view::{Selector, View};
+use Printer;
 
 /// Generic wrapper around a view.
 ///
@@ -78,7 +79,7 @@ pub trait ViewWrapper: 'static {
 
     /// Wraps the `find` method.
     fn wrap_call_on_any<'a>(
-        &mut self, selector: &Selector, callback: Box<FnMut(&mut Any) + 'a>
+        &mut self, selector: &Selector, callback: AnyCb<'a>,
     ) {
         self.with_view_mut(|v| v.call_on_any(selector, callback));
     }
@@ -93,6 +94,12 @@ pub trait ViewWrapper: 'static {
     fn wrap_needs_relayout(&self) -> bool {
         self.with_view(|v| v.needs_relayout()).unwrap_or(true)
     }
+
+    /// Wraps the `important_area` method.
+    fn wrap_important_area(&self, size: Vec2) -> Rect {
+        self.with_view(|v| v.important_area(size))
+            .unwrap_or_else(|| Rect::from((0, 0)))
+    }
 }
 
 // The main point of implementing ViewWrapper is to have View for free.
@@ -118,7 +125,7 @@ impl<T: ViewWrapper> View for T {
     }
 
     fn call_on_any<'a>(
-        &mut self, selector: &Selector, callback: Box<FnMut(&mut Any) + 'a>
+        &mut self, selector: &Selector, callback: Box<FnMut(&mut Any) + 'a>,
     ) {
         self.wrap_call_on_any(selector, callback)
     }
@@ -130,6 +137,10 @@ impl<T: ViewWrapper> View for T {
     fn focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
         self.wrap_focus_view(selector)
     }
+
+    fn important_area(&self, size: Vec2) -> Rect {
+        self.wrap_important_area(size)
+    }
 }
 
 /// Convenient macro to implement the [`ViewWrapper`] trait.

src/views/box_view.rs

@@ -1,6 +1,6 @@
-use XY;
 use vec::Vec2;
 use view::{SizeConstraint, View, ViewWrapper};
+use XY;
 
 /// Wrapper around another view, with a controlled size.
 ///
@@ -39,7 +39,7 @@ impl<T: View> BoxView<T> {
     ///
     /// `None` values will use the wrapped view's preferences.
     pub fn new(
-        width: SizeConstraint, height: SizeConstraint, view: T
+        width: SizeConstraint, height: SizeConstraint, view: T,
     ) -> Self {
         BoxView {
             size: (width, height).into(),
@@ -50,7 +50,7 @@ impl<T: View> BoxView<T> {
 
     /// Sets the size constraints for this view.
     pub fn set_constraints(
-        &mut self, width: SizeConstraint, height: SizeConstraint
+        &mut self, width: SizeConstraint, height: SizeConstraint,
     ) {
         self.set_width(width);
         self.set_height(height);
@@ -195,7 +195,8 @@ impl<T: View> ViewWrapper for BoxView<T> {
         let req = self.size.zip_map(req, SizeConstraint::available);
         let child_size = self.view.required_size(req);
 
-        let result = self.size
+        let result = self
+            .size
             .zip_map(child_size.zip(req), SizeConstraint::result);
 
         debug!("{:?}", result);

src/views/button.rs

@@ -1,11 +1,12 @@
-use {Cursive, Printer, With};
 use align::HAlign;
 use direction::Direction;
 use event::*;
+use rect::Rect;
 use theme::ColorStyle;
 use unicode_width::UnicodeWidthStr;
 use vec::Vec2;
 use view::View;
+use {Cursive, Printer, With};
 
 /// Simple text label with a callback when <Enter> is pressed.
 ///
@@ -21,6 +22,7 @@ pub struct Button {
     label: String,
     callback: Callback,
     enabled: bool,
+    last_size: Vec2,
 }
 
 impl Button {
@@ -43,6 +45,7 @@ impl Button {
             label: label.into(),
             callback: Callback::from_fn(cb),
             enabled: true,
+            last_size: Vec2::zero(),
         }
     }
 
@@ -140,13 +143,17 @@ impl View for Button {
         };
 
         let offset =
-            HAlign::Center.get_offset(self.label.len(), printer.size.x);
+            HAlign::Center.get_offset(self.label.width(), printer.size.x);
 
         printer.with_color(style, |printer| {
             printer.print((offset, 0), &self.label);
         });
     }
 
+    fn layout(&mut self, size: Vec2) {
+        self.last_size = size;
+    }
+
     fn required_size(&mut self, _: Vec2) -> Vec2 {
         // Meh. Fixed size we are.
         self.req_size()
@@ -155,6 +162,8 @@ impl View for Button {
     fn on_event(&mut self, event: Event) -> EventResult {
         // eprintln!("{:?}", event);
         // eprintln!("{:?}", self.req_size());
+        let width = self.label.width();
+        let self_offset = HAlign::Center.get_offset(width, self.last_size.x);
         match event {
             // 10 is the ascii code for '\n', that is the return key
             Event::Key(Key::Enter) => {
@@ -164,7 +173,8 @@ impl View for Button {
                 event: MouseEvent::Release(MouseButton::Left),
                 position,
                 offset,
-            } if position.fits_in_rect(offset, self.req_size()) =>
+            } if position
+                .fits_in_rect(offset + (self_offset, 0), self.req_size()) =>
             {
                 EventResult::Consumed(Some(self.callback.clone()))
             }
@@ -175,4 +185,11 @@ impl View for Button {
     fn take_focus(&mut self, _: Direction) -> bool {
         self.enabled
     }
+
+    fn important_area(&self, view_size: Vec2) -> Rect {
+        let width = self.label.width();
+        let offset = HAlign::Center.get_offset(width, view_size.x);
+
+        Rect::from_size((offset, 0), (width, 1))
+    }
 }

src/views/canvas.rs

@@ -1,9 +1,10 @@
+use direction::Direction;
+use event::{AnyCb, Event, EventResult};
+use rect::Rect;
+use vec::Vec2;
+use view::{Selector, View};
 use Printer;
 use With;
-use direction::Direction;
-use event::{Event, EventResult};
-use vec::Vec2;
-use view::View;
 
 /// A blank view that forwards calls to closures.
 ///
@@ -17,6 +18,9 @@ pub struct Canvas<T> {
     layout: Box<FnMut(&mut T, Vec2)>,
     take_focus: Box<FnMut(&mut T, Direction) -> bool>,
     needs_relayout: Box<Fn(&T) -> bool>,
+    focus_view: Box<FnMut(&mut T, &Selector) -> Result<(), ()>>,
+    call_on_any: Box<for<'a> FnMut(&mut T, &Selector, AnyCb<'a>)>,
+    important_area: Box<Fn(&T, Vec2) -> Rect>,
 }
 
 impl<T: 'static + View> Canvas<T> {
@@ -31,6 +35,9 @@ impl<T: 'static + View> Canvas<T> {
             .with_layout(T::layout)
             .with_take_focus(T::take_focus)
             .with_needs_relayout(T::needs_relayout)
+            .with_focus_view(T::focus_view)
+            .with_call_on_any(T::call_on_any)
+            .with_important_area(T::important_area)
     }
 }
 
@@ -55,6 +62,11 @@ impl<T> Canvas<T> {
             layout: Box::new(|_, _| ()),
             take_focus: Box::new(|_, _| false),
             needs_relayout: Box::new(|_| true),
+            focus_view: Box::new(|_, _| Err(())),
+            call_on_any: Box::new(|_, _, _| ()),
+            important_area: Box::new(|_, size| {
+                Rect::from_corners((0, 0), size)
+            }),
         }
     }
 
@@ -170,6 +182,60 @@ impl<T> Canvas<T> {
     {
         self.with(|s| s.set_needs_relayout(f))
     }
+
+    /// Sets the closure for `call_on_any()`.
+    pub fn set_call_on_any<F>(&mut self, f: F)
+    where
+        F: 'static + for<'a> FnMut(&mut T, &Selector, AnyCb<'a>),
+    {
+        self.call_on_any = Box::new(f);
+    }
+
+    /// Sets the closure for `call_on_any()`.
+    ///
+    /// Chainable variant.
+    pub fn with_call_on_any<F>(self, f: F) -> Self
+    where
+        F: 'static + for<'a> FnMut(&mut T, &Selector, AnyCb<'a>),
+    {
+        self.with(|s| s.set_call_on_any(f))
+    }
+
+    /// Sets the closure for `important_area()`.
+    pub fn set_important_area<F>(&mut self, f: F)
+    where
+        F: 'static + Fn(&T, Vec2) -> Rect,
+    {
+        self.important_area = Box::new(f);
+    }
+
+    /// Sets the closure for `important_area()`.
+    ///
+    /// Chainable variant.
+    pub fn with_important_area<F>(self, f: F) -> Self
+    where
+        F: 'static + Fn(&T, Vec2) -> Rect,
+    {
+        self.with(|s| s.set_important_area(f))
+    }
+
+    /// Sets the closure for `focus_view()`.
+    pub fn set_focus_view<F>(&mut self, f: F)
+    where
+        F: 'static + FnMut(&mut T, &Selector) -> Result<(), ()>,
+    {
+        self.focus_view = Box::new(f);
+    }
+
+    /// Sets the closure for `focus_view()`.
+    ///
+    /// Chainable variant.
+    pub fn with_focus_view<F>(self, f: F) -> Self
+    where
+        F: 'static + FnMut(&mut T, &Selector) -> Result<(), ()>,
+    {
+        self.with(|s| s.set_focus_view(f))
+    }
 }
 
 impl<T: 'static> View for Canvas<T> {
@@ -192,4 +258,20 @@ impl<T: 'static> View for Canvas<T> {
     fn take_focus(&mut self, source: Direction) -> bool {
         (self.take_focus)(&mut self.state, source)
     }
+
+    fn needs_relayout(&self) -> bool {
+        (self.needs_relayout)(&self.state)
+    }
+
+    fn focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
+        (self.focus_view)(&mut self.state, selector)
+    }
+
+    fn important_area(&self, view_size: Vec2) -> Rect {
+        (self.important_area)(&self.state, view_size)
+    }
+
+    fn call_on_any<'a>(&mut self, selector: &Selector, cb: AnyCb<'a>) {
+        (self.call_on_any)(&mut self.state, selector, cb);
+    }
 }

src/views/checkbox.rs

@@ -1,12 +1,12 @@
-use Cursive;
-use Printer;
-use With;
 use direction::Direction;
 use event::{Event, EventResult, Key, MouseButton, MouseEvent};
 use std::rc::Rc;
 use theme::ColorStyle;
 use vec::Vec2;
 use view::View;
+use Cursive;
+use Printer;
+use With;
 
 /// Checkable box.
 pub struct Checkbox {
@@ -32,7 +32,7 @@ impl Checkbox {
 
     /// Sets a callback to be used when the state changes.
     pub fn set_on_change<F: 'static + Fn(&mut Cursive, bool)>(
-        &mut self, on_change: F
+        &mut self, on_change: F,
     ) {
         self.on_change = Some(Rc::new(on_change));
     }
@@ -41,7 +41,7 @@ impl Checkbox {
     ///
     /// Chainable variant.
     pub fn on_change<F: 'static + Fn(&mut Cursive, bool)>(
-        self, on_change: F
+        self, on_change: F,
     ) -> Self {
         self.with(|s| s.set_on_change(on_change))
     }

src/views/dialog.rs

@@ -1,10 +1,7 @@
-use Cursive;
-use Printer;
-use With;
 use align::*;
 use direction::Direction;
-use event::*;
-use std::any::Any;
+use event::{AnyCb, Event, EventResult, Key};
+use rect::Rect;
 use std::cell::Cell;
 use std::cmp::max;
 use theme::ColorStyle;
@@ -12,6 +9,9 @@ use unicode_width::UnicodeWidthStr;
 use vec::Vec2;
 use view::{Margins, Selector, View};
 use views::{Button, DummyView, SizedView, TextView, ViewBox};
+use Cursive;
+use Printer;
+use With;
 
 /// Identifies currently focused element in [`Dialog`].
 ///
@@ -246,7 +246,7 @@ impl Dialog {
 
     /// Returns an iterator on this buttons for this dialog.
     pub fn buttons_mut<'a>(
-        &'a mut self
+        &'a mut self,
     ) -> Box<'a + Iterator<Item = &'a mut Button>> {
         Box::new(self.buttons.iter_mut().map(|b| &mut b.button.view))
     }
@@ -281,7 +281,7 @@ impl Dialog {
 
     // An event is received while a button is in focus
     fn on_event_button(
-        &mut self, event: Event, button_id: usize
+        &mut self, event: Event, button_id: usize,
     ) -> EventResult {
         let result = {
             let button = &mut self.buttons[button_id];
@@ -340,7 +340,8 @@ impl Dialog {
         // Current horizontal position of the next button we'll draw.
 
         // Sum of the sizes + len-1 for margins
-        let width = self.buttons
+        let width = self
+            .buttons
             .iter()
             .map(|button| button.button.size.x)
             .sum::<usize>()
@@ -350,7 +351,8 @@ impl Dialog {
             return None;
         }
         let mut offset = overhead.left
-            + self.align
+            + self
+                .align
                 .h
                 .get_offset(width, printer.size.x - overhead.horizontal());
 
@@ -366,11 +368,10 @@ impl Dialog {
             // Add some special effect to the focused button
             let position = Vec2::new(offset, y);
             button.offset.set(position);
-            button.button.draw(&printer.sub_printer(
-                position,
-                size,
-                self.focus == DialogFocus::Button(i),
-            ));
+            button.button.draw(&printer
+                .offset(position)
+                .cropped(size)
+                .focused(self.focus == DialogFocus::Button(i)));
             // Keep 1 blank between two buttons
             offset += size.x + 1;
             // Also keep 1 blank above the buttons
@@ -382,7 +383,8 @@ impl Dialog {
 
     fn draw_content(&self, printer: &Printer, buttons_height: usize) {
         // What do we have left?
-        let taken = Vec2::new(0, buttons_height) + self.borders.combined()
+        let taken = Vec2::new(0, buttons_height)
+            + self.borders.combined()
             + self.padding.combined();
 
         let inner_size = match printer.size.checked_sub(taken) {
@@ -390,11 +392,10 @@ impl Dialog {
             None => return,
         };
 
-        self.content.draw(&printer.sub_printer(
-            self.borders.top_left() + self.padding.top_left(),
-            inner_size,
-            self.focus == DialogFocus::Content,
-        ));
+        self.content.draw(&printer
+            .offset(self.borders.top_left() + self.padding.top_left())
+            .cropped(inner_size)
+            .focused(self.focus == DialogFocus::Content));
     }
 
     fn draw_title(&self, printer: &Printer) {
@@ -405,7 +406,8 @@ impl Dialog {
             }
             let spacing = 3; //minimum distance to borders
             let x = spacing
-                + self.title_position
+                + self
+                    .title_position
                     .get_offset(len, printer.size.x - 2 * spacing);
             printer.with_high_border(false, |printer| {
                 printer.print((x - 2, 0), "┤ ");
@@ -563,13 +565,16 @@ impl View for Dialog {
         }
     }
 
-    fn call_on_any<'a>(
-        &mut self, selector: &Selector, callback: Box<FnMut(&mut Any) + 'a>
-    ) {
+    fn call_on_any<'a>(&mut self, selector: &Selector, callback: AnyCb<'a>) {
         self.content.call_on_any(selector, callback);
     }
 
     fn focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
         self.content.focus_view(selector)
     }
+
+    fn important_area(&self, _: Vec2) -> Rect {
+        self.content.important_area(self.content.size)
+            + self.borders.top_left() + self.padding.top_left()
+    }
 }

src/views/dummy.rs

@@ -1,5 +1,5 @@
-use Printer;
 use view::View;
+use Printer;
 
 /// Dummy view.
 ///

src/views/edit_view.rs

@@ -1,5 +1,6 @@
 use direction::Direction;
 use event::{Callback, Event, EventResult, Key, MouseEvent};
+use rect::Rect;
 use std::cell::RefCell;
 use std::rc::Rc;
 use theme::{ColorStyle, Effect};
@@ -367,8 +368,7 @@ impl EditView {
         self.offset = 0;
         self.set_cursor(len);
 
-        self.make_edit_cb()
-            .unwrap_or_else(Callback::dummy)
+        self.make_edit_cb().unwrap_or_else(Callback::dummy)
     }
 
     /// Get the current text.
@@ -420,8 +420,7 @@ impl EditView {
 
         self.keep_cursor_in_view();
 
-        self.make_edit_cb()
-            .unwrap_or_else(Callback::dummy)
+        self.make_edit_cb().unwrap_or_else(Callback::dummy)
     }
 
     /// Remove the character at the current cursor position.
@@ -436,8 +435,7 @@ impl EditView {
 
         self.keep_cursor_in_view();
 
-        self.make_edit_cb()
-            .unwrap_or_else(Callback::dummy)
+        self.make_edit_cb().unwrap_or_else(Callback::dummy)
     }
 
     fn make_edit_cb(&self) -> Option<Callback> {
@@ -672,13 +670,13 @@ impl View for EditView {
                 offset,
             } if position.fits_in_rect(offset, (self.last_length, 1)) =>
             {
-                position.checked_sub(offset).map(|position| {
+                if let Some(position) = position.checked_sub(offset) {
                     self.cursor = self.offset
                         + simple_prefix(
                             &self.content[self.offset..],
                             position.x,
                         ).length;
-                });
+                }
             }
             _ => return EventResult::Ignored,
         }
@@ -687,4 +685,22 @@ impl View for EditView {
 
         EventResult::Consumed(self.make_edit_cb())
     }
+
+    fn important_area(&self, _: Vec2) -> Rect {
+        let char_width = if self.cursor >= self.content.len() {
+            // Show a space if we're at the end of the content
+            1
+        } else {
+            // Otherwise look at the selected character.
+            self.content[self.cursor..]
+                .graphemes(true)
+                .next()
+                .unwrap()
+                .width()
+        };
+
+        let x = self.content[..self.cursor].width();
+
+        Rect::from_size((x, 0), (char_width, 1))
+    }
 }

src/views/hideable_view.rs

@@ -0,0 +1,94 @@
+use view::{Selector, View, ViewWrapper};
+use With;
+
+use std::any::Any;
+
+/// Wrapper around another view that can be hidden at will.
+///
+/// By default, it simply forwards all calls to the inner view.
+///
+/// When hidden (with `HideableView::hide()`), it will appear as a zero-sized
+/// invisible view, will not take focus and will not accept input.
+///
+/// It can be made visible again with `HideableView::unhide()`.
+pub struct HideableView<V> {
+    view: V,
+    visible: bool,
+}
+
+impl<V> HideableView<V> {
+    /// Creates a new HideableView around `view`.
+    ///
+    /// It will be visible by default.
+    pub fn new(view: V) -> Self {
+        HideableView {
+            view,
+            visible: true,
+        }
+    }
+
+    /// Sets the visibility for this view.
+    pub fn set_visible(&mut self, visible: bool) {
+        self.visible = visible;
+    }
+
+    /// Sets the visibility for this view to `false`.
+    pub fn hide(&mut self) {
+        self.set_visible(false);
+    }
+
+    /// Sets the visibility for this view to `true`.
+    pub fn unhide(&mut self) {
+        self.set_visible(true);
+    }
+
+    /// Sets the visibility for this view to `false`.
+    ///
+    /// Chainable variant.
+    pub fn hidden(self) -> Self {
+        self.with(Self::hide)
+    }
+
+    inner_getters!(self.view: V);
+}
+
+impl<V: View> ViewWrapper for HideableView<V> {
+    type V = V;
+
+    fn with_view<F, R>(&self, f: F) -> Option<R>
+    where
+        F: FnOnce(&Self::V) -> R,
+    {
+        if self.visible {
+            Some(f(&self.view))
+        } else {
+            None
+        }
+    }
+
+    fn with_view_mut<F, R>(&mut self, f: F) -> Option<R>
+    where
+        F: FnOnce(&mut Self::V) -> R,
+    {
+        if self.visible {
+            Some(f(&mut self.view))
+        } else {
+            None
+        }
+    }
+
+    fn wrap_call_on_any<'a>(
+        &mut self, selector: &Selector, callback: Box<FnMut(&mut Any) + 'a>,
+    ) {
+        // We always run callbacks, even when invisible.
+        self.view.call_on_any(selector, callback)
+    }
+
+    fn into_inner(self) -> Result<Self::V, Self>
+    where
+        Self: Sized,
+        Self::V: Sized,
+    {
+        Ok(self.view)
+    }
+}

src/views/id_view.rs

@@ -77,15 +77,14 @@ impl<T: View + 'static> ViewWrapper for IdView<T> {
 
     // Some for<'b> weirdness here to please the borrow checker gods...
     fn wrap_call_on_any<'a>(
-        &mut self, selector: &Selector, mut callback: BoxedCallback<'a>
+        &mut self, selector: &Selector, mut callback: BoxedCallback<'a>,
     ) {
         match selector {
             &Selector::Id(id) if id == self.id => callback(self),
             s => {
-                self.view
-                    .try_borrow_mut()
-                    .ok()
-                    .map(|mut v| v.deref_mut().call_on_any(s, callback));
+                if let Ok(mut v) = self.view.try_borrow_mut() {
+                    v.deref_mut().call_on_any(s, callback);
+                }
             }
         }
     }
@@ -93,7 +92,8 @@ impl<T: View + 'static> ViewWrapper for IdView<T> {
     fn wrap_focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
         match selector {
             &Selector::Id(id) if id == self.id => Ok(()),
-            s => self.view
+            s => self
+                .view
                 .try_borrow_mut()
                 .map_err(|_| ())
                 .and_then(|mut v| v.deref_mut().focus_view(s)),

src/views/layer.rs

@@ -1,5 +1,5 @@
-use Printer;
 use view::{View, ViewWrapper};
+use Printer;
 
 /// Wrapper view that fills the background.
 ///
@@ -14,7 +14,7 @@ pub struct Layer<T: View> {
 impl<T: View> Layer<T> {
     /// Wraps the given view.
     pub fn new(view: T) -> Self {
-        Layer { view: view }
+        Layer { view }
     }
 
     inner_getters!(self.view: T);

src/views/linear_layout.rs

@@ -1,13 +1,13 @@
-use Printer;
-use With;
-use XY;
 use direction;
-use event::{Event, EventResult, Key};
-use std::any::Any;
+use event::{AnyCb, Event, EventResult, Key};
+use rect::Rect;
 use std::cmp::min;
 use std::ops::Deref;
 use vec::Vec2;
 use view::{Selector, SizeCache, View};
+use Printer;
+use With;
+use XY;
 
 /// Arranges its children linearly according to its orientation.
 pub struct LinearLayout {
@@ -57,7 +57,7 @@ struct ChildItem<T> {
 
 impl<T> ChildIterator<T> {
     fn new(
-        inner: T, orientation: direction::Orientation, available: usize
+        inner: T, orientation: direction::Orientation, available: usize,
     ) -> Self {
         ChildIterator {
             inner,
@@ -195,7 +195,8 @@ impl LinearLayout {
     }
 
     fn children_are_sleeping(&self) -> bool {
-        !self.children
+        !self
+            .children
             .iter()
             .map(Child::as_view)
             .any(View::needs_relayout)
@@ -203,7 +204,7 @@ impl LinearLayout {
 
     /// Returns a cyclic mutable iterator starting with the child in focus
     fn iter_mut<'a>(
-        &'a mut self, from_focus: bool, source: direction::Relative
+        &'a mut self, from_focus: bool, source: direction::Relative,
     ) -> Box<Iterator<Item = (usize, &mut Child)> + 'a> {
         match source {
             direction::Relative::Front => {
@@ -279,11 +280,11 @@ impl LinearLayout {
                 // this will give us the allowed window for a click.
                 let child_size = item.child.size.get(self.orientation);
 
-                if (item.offset + child_size > position)
-                    && item.child.view.take_focus(direction::Direction::none())
-                {
-                    // eprintln!("It's a match!");
-                    self.focus = i;
+                if item.offset + child_size > position {
+                    if item.child.view.take_focus(direction::Direction::none())
+                    {
+                        self.focus = i;
+                    }
                     return;
                 }
             }
@@ -292,7 +293,7 @@ impl LinearLayout {
 }
 
 fn try_focus(
-    (i, child): (usize, &mut Child), source: direction::Direction
+    (i, child): (usize, &mut Child), source: direction::Direction,
 ) -> Option<usize> {
     if child.view.take_focus(source) {
         Some(i)
@@ -314,11 +315,10 @@ impl View for LinearLayout {
             // eprintln!("Printer size: {:?}", printer.size);
             // eprintln!("Child size: {:?}", item.child.size);
             // eprintln!("Offset: {:?}", item.offset);
-            let printer = &printer.sub_printer(
-                self.orientation.make_vec(item.offset, 0),
-                item.child.size,
-                i == self.focus,
-            );
+            let printer = &printer
+                .offset(self.orientation.make_vec(item.offset, 0))
+                .cropped(item.child.size)
+                .focused(i == self.focus);
             item.child.view.draw(printer);
         }
     }
@@ -358,7 +358,8 @@ impl View for LinearLayout {
         }
 
         // First, make a naive scenario: everything will work fine.
-        let ideal_sizes: Vec<Vec2> = self.children
+        let ideal_sizes: Vec<Vec2> = self
+            .children
             .iter_mut()
             .map(|c| c.required_size(req))
             .collect();
@@ -382,7 +383,8 @@ impl View for LinearLayout {
 
         // See how they like it that way.
         // This is, hopefully, the absolute minimum these views will accept.
-        let min_sizes: Vec<Vec2> = self.children
+        let min_sizes: Vec<Vec2> = self
+            .children
             .iter_mut()
             .map(|c| c.required_size(budget_req))
             .collect();
@@ -462,7 +464,8 @@ impl View for LinearLayout {
 
         // Let's ask everyone one last time. Everyone should be happy.
         // (But they may ask more on the other axis.)
-        let final_sizes: Vec<Vec2> = self.children
+        let final_sizes: Vec<Vec2> = self
+            .children
             .iter_mut()
             .enumerate()
             .map(|(i, c)| c.required_size(final_lengths[i]))
@@ -482,10 +485,9 @@ impl View for LinearLayout {
         // In what order will we iterate on the children?
         let rel = source.relative(self.orientation);
         // We activate from_focus only if coming from the "sides".
-        let i = if let Some(i) = self.iter_mut(
-            rel.is_none(),
-            rel.unwrap_or(direction::Relative::Front),
-        ).filter_map(|p| try_focus(p, source))
+        let i = if let Some(i) = self
+            .iter_mut(rel.is_none(), rel.unwrap_or(direction::Relative::Front))
+            .filter_map(|p| try_focus(p, source))
             .next()
         {
             // ... we can't update `self.focus` here,
@@ -554,8 +556,7 @@ impl View for LinearLayout {
     }
 
     fn call_on_any<'a>(
-        &mut self, selector: &Selector,
-        mut callback: Box<FnMut(&mut Any) + 'a>,
+        &mut self, selector: &Selector, mut callback: AnyCb<'a>,
     ) {
         for child in &mut self.children {
             child
@@ -574,4 +575,30 @@ impl View for LinearLayout {
 
         Err(())
     }
+
+    fn important_area(&self, _: Vec2) -> Rect {
+        if self.children.is_empty() {
+            // Return dummy area if we are empty.
+            return Rect::from((0, 0));
+        }
+
+        // Pick the focused item, with its offset
+        let item = {
+            let mut iterator = ChildIterator::new(
+                self.children.iter(),
+                self.orientation,
+                usize::max_value(),
+            );
+            iterator.nth(self.focus).unwrap()
+        };
+
+        // Make a vector offset from the scalar value
+        let offset = self.orientation.make_vec(item.offset, 0);
+
+        // And ask the child its own area.
+        let rect = item.child.view.important_area(item.child.size);
+
+        // Add `offset` to the rect.
+        rect + offset
+    }
 }

src/views/list_view.rs

@@ -1,13 +1,15 @@
-use Cursive;
-use Printer;
-use With;
 use direction;
-use event::{Callback, Event, EventResult, Key, MouseButton, MouseEvent};
-use std::any::Any;
+use event::{
+    AnyCb, Callback, Event, EventResult, Key, MouseButton, MouseEvent,
+};
+use rect::Rect;
 use std::rc::Rc;
 use unicode_width::UnicodeWidthStr;
 use vec::Vec2;
 use view::{ScrollBase, Selector, View};
+use Cursive;
+use Printer;
+use With;
 
 /// Represents a child from a [`ListView`].
 ///
@@ -148,7 +150,7 @@ impl ListView {
     }
 
     fn iter_mut<'a>(
-        &'a mut self, from_focus: bool, source: direction::Relative
+        &'a mut self, from_focus: bool, source: direction::Relative,
     ) -> Box<Iterator<Item = (usize, &mut ListChild)> + 'a> {
         match source {
             direction::Relative::Front => {
@@ -172,7 +174,7 @@ impl ListView {
     }
 
     fn move_focus(
-        &mut self, n: usize, source: direction::Direction
+        &mut self, n: usize, source: direction::Direction,
     ) -> EventResult {
         let i = if let Some(i) = source
             .relative(direction::Orientation::Vertical)
@@ -246,7 +248,7 @@ impl ListView {
 }
 
 fn try_focus(
-    (i, child): (usize, &mut ListChild), source: direction::Direction
+    (i, child): (usize, &mut ListChild), source: direction::Direction,
 ) -> Option<usize> {
     match *child {
         ListChild::Delimiter => None,
@@ -271,7 +273,9 @@ impl View for ListView {
             .draw(printer, |printer, i| match self.children[i] {
                 ListChild::Row(ref label, ref view) => {
                     printer.print((0, 0), label);
-                    view.draw(&printer.offset((offset, 0), i == self.focus));
+                    view.draw(&printer
+                        .offset((offset, 0))
+                        .focused(i == self.focus));
                 }
                 ListChild::Delimiter => (),
             });
@@ -279,14 +283,16 @@ impl View for ListView {
 
     fn required_size(&mut self, req: Vec2) -> Vec2 {
         // We'll show 2 columns: the labels, and the views.
-        let label_width = self.children
+        let label_width = self
+            .children
             .iter()
             .map(ListChild::label)
             .map(UnicodeWidthStr::width)
             .max()
             .unwrap_or(0);
 
-        let view_size = self.children
+        let view_size = self
+            .children
             .iter_mut()
             .filter_map(ListChild::view)
             .map(|v| v.required_size(req).x)
@@ -306,7 +312,8 @@ impl View for ListView {
         self.scrollbase.set_heights(size.y, self.children.len());
 
         // We'll show 2 columns: the labels, and the views.
-        let label_width = self.children
+        let label_width = self
+            .children
             .iter()
             .map(ListChild::label)
             .map(UnicodeWidthStr::width)
@@ -316,7 +323,8 @@ impl View for ListView {
         let spacing = 1;
         let scrollbar_width = if self.children.len() > size.y { 2 } else { 0 };
 
-        let available = size.x
+        let available = size
+            .x
             .saturating_sub(label_width + spacing + scrollbar_width);
 
         debug!("Available: {}", available);
@@ -399,12 +407,10 @@ impl View for ListView {
             Event::Key(Key::PageDown) => {
                 self.move_focus(10, direction::Direction::up())
             }
-            Event::Key(Key::Home) | Event::Ctrl(Key::Home) => {
-                self.move_focus(
-                    usize::max_value(),
-                    direction::Direction::back(),
-                )
-            }
+            Event::Key(Key::Home) | Event::Ctrl(Key::Home) => self.move_focus(
+                usize::max_value(),
+                direction::Direction::back(),
+            ),
             Event::Key(Key::End) | Event::Ctrl(Key::End) => self.move_focus(
                 usize::max_value(),
                 direction::Direction::front(),
@@ -437,10 +443,9 @@ impl View for ListView {
 
     fn take_focus(&mut self, source: direction::Direction) -> bool {
         let rel = source.relative(direction::Orientation::Vertical);
-        let i = if let Some(i) = self.iter_mut(
-            rel.is_none(),
-            rel.unwrap_or(direction::Relative::Front),
-        ).filter_map(|p| try_focus(p, source))
+        let i = if let Some(i) = self
+            .iter_mut(rel.is_none(), rel.unwrap_or(direction::Relative::Front))
+            .filter_map(|p| try_focus(p, source))
             .next()
         {
             i
@@ -454,8 +459,7 @@ impl View for ListView {
     }
 
     fn call_on_any<'a>(
-        &mut self, selector: &Selector,
-        mut callback: Box<FnMut(&mut Any) + 'a>,
+        &mut self, selector: &Selector, mut callback: AnyCb<'a>,
     ) {
         for view in self.children.iter_mut().filter_map(ListChild::view) {
             view.call_on_any(selector, Box::new(|any| callback(any)));
@@ -463,7 +467,8 @@ impl View for ListView {
     }
 
     fn focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
-        if let Some(i) = self.children
+        if let Some(i) = self
+            .children
             .iter_mut()
             .enumerate()
             .filter_map(|(i, v)| v.view().map(|v| (i, v)))
@@ -476,4 +481,22 @@ impl View for ListView {
             Err(())
         }
     }
+
+    fn important_area(&self, size: Vec2) -> Rect {
+        if self.children.is_empty() {
+            return Rect::from((0, 0));
+        }
+
+        let labels_width = self.labels_width();
+
+        let area = match self.children[self.focus] {
+            ListChild::Row(_, ref view) => {
+                let available = Vec2::new(size.x - labels_width - 1, 1);
+                view.important_area(available) + (labels_width, 0)
+            }
+            ListChild::Delimiter => Rect::from_size((0, 0), (size.x, 1)),
+        };
+
+        area + (0, self.focus)
+    }
 }

src/views/menu_popup.rs

@@ -1,15 +1,16 @@
-use Cursive;
-use Printer;
-use With;
 use align::Align;
 use event::{Callback, Event, EventResult, Key, MouseButton, MouseEvent};
 use menu::{MenuItem, MenuTree};
+use rect::Rect;
 use std::cmp::min;
 use std::rc::Rc;
 use unicode_width::UnicodeWidthStr;
 use vec::Vec2;
 use view::{Position, ScrollBase, View};
 use views::OnEventView;
+use Cursive;
+use Printer;
+use With;
 
 /// Popup that shows a list of items.
 pub struct MenuPopup {
@@ -137,13 +138,13 @@ impl MenuPopup {
 
     fn make_subtree_cb(&self, tree: &Rc<MenuTree>) -> EventResult {
         let tree = Rc::clone(tree);
-        let max_width = 4
-            + self.menu
-                .children
-                .iter()
-                .map(Self::item_width)
-                .max()
-                .unwrap_or(1);
+        let max_width = 4 + self
+            .menu
+            .children
+            .iter()
+            .map(Self::item_width)
+            .max()
+            .unwrap_or(1);
         let offset = Vec2::new(max_width, self.focus);
         let action_cb = self.on_action.clone();
 
@@ -209,7 +210,7 @@ impl View for MenuPopup {
         let h = self.menu.len();
         // If we're too high, add a vertical offset
         let offset = self.align.v.get_offset(h, printer.size.y);
-        let printer = &printer.offset((0, offset), true);
+        let printer = &printer.offset((0, offset));
 
         // Start with a box
         printer.print_box(Vec2::new(0, 0), printer.size, false);
@@ -217,8 +218,7 @@ impl View for MenuPopup {
         // We're giving it a reduced size because of borders.
         // But we're keeping the full width,
         // to integrate horizontal delimiters in the frame.
-        let size = printer.size - (0, 2);
-        let printer = printer.sub_printer((0, 1), size, true);
+        let printer = printer.offset((0, 1)).shrinked((0, 1));
 
         self.scrollbase.draw(&printer, |printer, i| {
             printer.with_selection(i == self.focus, |printer| {
@@ -250,13 +250,13 @@ impl View for MenuPopup {
 
     fn required_size(&mut self, req: Vec2) -> Vec2 {
         // We can't really shrink our items here, so it's not flexible.
-        let w = 4
-            + self.menu
-                .children
-                .iter()
-                .map(Self::item_width)
-                .max()
-                .unwrap_or(1);
+        let w = 4 + self
+            .menu
+            .children
+            .iter()
+            .map(Self::item_width)
+            .max()
+            .unwrap_or(1);
         let h = 2 + self.menu.children.len();
 
         let scrolling = req.y < h;
@@ -343,19 +343,16 @@ impl View for MenuPopup {
                 // eprintln!("Position: {:?} / {:?}", position, offset);
                 // eprintln!("Last size: {:?}", self.last_size);
                 let inner_size = self.last_size.saturating_sub((2, 2));
-                position.checked_sub(offset + (1, 1)).map(
+                if let Some(position) = position.checked_sub(offset + (1, 1)) {
                     // `position` is not relative to the content
                     // (It's inside the border)
-                    |position| {
-                        if position < inner_size {
-                            let focus =
-                                position.y + self.scrollbase.start_line;
-                            if !self.menu.children[focus].is_delimiter() {
-                                self.focus = focus;
-                            }
+                    if position < inner_size {
+                        let focus = position.y + self.scrollbase.start_line;
+                        if !self.menu.children[focus].is_delimiter() {
+                            self.focus = focus;
                         }
-                    },
-                );
+                    }
+                }
             }
             Event::Mouse {
                 event: MouseEvent::Release(MouseButton::Left),
@@ -400,4 +397,12 @@ impl View for MenuPopup {
         self.scrollbase
             .set_heights(size.y.saturating_sub(2), self.menu.children.len());
     }
+
+    fn important_area(&self, size: Vec2) -> Rect {
+        if self.menu.is_empty() {
+            return Rect::from((0, 0));
+        }
+
+        Rect::from_size((0, self.focus), (size.x, 1))
+    }
 }

src/views/menubar.rs

@@ -1,14 +1,15 @@
-use Cursive;
-use Printer;
 use direction;
 use event::*;
 use menu::{MenuItem, MenuTree};
+use rect::Rect;
 use std::rc::Rc;
 use theme::ColorStyle;
 use unicode_width::UnicodeWidthStr;
 use vec::Vec2;
 use view::{Position, View};
 use views::{MenuPopup, OnEventView};
+use Cursive;
+use Printer;
 
 /// Current state of the menubar
 #[derive(PartialEq, Debug)]
@@ -106,7 +107,7 @@ impl Menubar {
 
     /// Insert a new item at the given position.
     pub fn insert_subtree<S>(
-        &mut self, i: usize, title: S, menu: MenuTree
+        &mut self, i: usize, title: S, menu: MenuTree,
     ) -> &mut Self
     where
         S: Into<String>,
@@ -341,7 +342,8 @@ impl View for Menubar {
                     .checked_sub(offset)
                     .and_then(|pos| self.child_at(pos.x))
                 {
-                    if self.focus == child && btn == MouseButton::Left
+                    if self.focus == child
+                        && btn == MouseButton::Left
                         && self.root.children[child].is_leaf()
                     {
                         return self.select_child(false);
@@ -371,7 +373,8 @@ impl View for Menubar {
         // We add 2 to the length of every label for marin.
         // Also, we add 1 at the beginning.
         // (See the `draw()` method)
-        let width = self.root
+        let width = self
+            .root
             .children
             .iter()
             .map(|item| item.label().len() + 2)
@@ -379,4 +382,21 @@ impl View for Menubar {
 
         Vec2::new(width, 1)
     }
+
+    fn important_area(&self, _: Vec2) -> Rect {
+        if self.root.is_empty() {
+            return Rect::from((0, 0));
+        }
+
+        // X position is 1 (margin before the first item) + sum of widths
+        // And each item has a 2 cells padding.
+        let x = 1 + self.root.children[..self.focus]
+            .iter()
+            .map(|child| child.label().width() + 2)
+            .sum::<usize>();
+
+        let width = self.root.children[self.focus].label().width();
+
+        Rect::from_size((x, 0), (width, 1))
+    }
 }

src/views/mod.rs

@@ -35,7 +35,6 @@ macro_rules! impl_enabled {
     }
 }
 
-mod view_box;
 mod box_view;
 mod button;
 mod canvas;
@@ -43,24 +42,27 @@ mod checkbox;
 mod dialog;
 mod dummy;
 mod edit_view;
+mod hideable_view;
 mod id_view;
-mod on_event_view;
 mod layer;
 mod linear_layout;
 mod list_view;
-mod menubar;
 mod menu_popup;
+mod menubar;
+mod on_event_view;
 mod panel;
 mod progress_bar;
 mod radio;
+mod scroll_view;
 mod select_view;
-mod slider_view;
 mod shadow_view;
 mod sized_view;
+mod slider_view;
 mod stack_view;
 mod text_area;
 mod text_view;
 mod tracked_view;
+mod view_box;
 
 pub use self::box_view::BoxView;
 pub use self::button::Button;
@@ -69,6 +71,7 @@ pub use self::checkbox::Checkbox;
 pub use self::dialog::{Dialog, DialogFocus};
 pub use self::dummy::DummyView;
 pub use self::edit_view::EditView;
+pub use self::hideable_view::HideableView;
 pub use self::id_view::{IdView, ViewRef};
 pub use self::layer::Layer;
 pub use self::linear_layout::LinearLayout;
@@ -79,6 +82,7 @@ pub use self::on_event_view::OnEventView;
 pub use self::panel::Panel;
 pub use self::progress_bar::ProgressBar;
 pub use self::radio::{RadioButton, RadioGroup};
+pub use self::scroll_view::ScrollView;
 pub use self::select_view::SelectView;
 pub use self::shadow_view::ShadowView;
 pub use self::sized_view::SizedView;

src/views/on_event_view.rs

@@ -1,9 +1,9 @@
-use Cursive;
-use With;
 use event::{Callback, Event, EventResult};
 use std::collections::HashMap;
 use std::rc::Rc;
 use view::{View, ViewWrapper};
+use Cursive;
+use With;
 
 /// A wrapper view that can react to events.
 ///

src/views/panel.rs

@@ -1,7 +1,8 @@
-use Printer;
 use event::{Event, EventResult};
+use rect::Rect;
 use vec::Vec2;
 use view::{View, ViewWrapper};
+use Printer;
 
 /// Draws a border around a wrapped view.
 #[derive(Debug)]
@@ -34,14 +35,16 @@ impl<V: View> ViewWrapper for Panel<V> {
 
     fn wrap_draw(&self, printer: &Printer) {
         printer.print_box((0, 0), printer.size, true);
-        self.view.draw(&printer.sub_printer(
-            (1, 1),
-            printer.size.saturating_sub((2, 2)),
-            true,
-        ));
+        let printer = printer.offset((1, 1)).shrinked((1, 1));
+        self.view.draw(&printer);
     }
 
     fn wrap_layout(&mut self, size: Vec2) {
         self.view.layout(size.saturating_sub((2, 2)));
     }
+
+    fn wrap_important_area(&self, size: Vec2) -> Rect {
+        let inner_size = size.saturating_sub((2, 2));
+        self.view.important_area(inner_size) + (1, 1)
+    }
 }

src/views/progress_bar.rs

@@ -1,10 +1,10 @@
-use Printer;
 use align::HAlign;
 use std::cmp;
 use std::thread;
 use theme::{ColorStyle, Effect};
 use utils::Counter;
 use view::View;
+use Printer;
 
 // pub type CbPromise = Option<Box<Fn(&mut Cursive) + Send>>;
 
@@ -96,7 +96,7 @@ impl ProgressBar {
     ///
     /// Chainable variant.
     pub fn with_task<F: FnOnce(Counter) + Send + 'static>(
-        mut self, task: F
+        mut self, task: F,
     ) -> Self {
         self.start(task);
         self
@@ -116,7 +116,7 @@ impl ProgressBar {
     /// }
     /// ```
     pub fn with_label<F: Fn(usize, (usize, usize)) -> String + 'static>(
-        mut self, label_maker: F
+        mut self, label_maker: F,
     ) -> Self {
         self.label_maker = Box::new(label_maker);
         self
@@ -188,7 +188,7 @@ impl View for ProgressBar {
             printer.with_effect(Effect::Reverse, |printer| {
                 printer.print((offset, 0), &label);
             });
-            let printer = &printer.sub_printer((0, 0), (length, 1), true);
+            let printer = &printer.cropped((length, 1));
             printer.print_hline((0, 0), length, " ");
             printer.print((offset, 0), &label);
         });

src/views/radio.rs

@@ -1,4 +1,3 @@
-use {Printer, With};
 use direction::Direction;
 use event::{Event, EventResult, Key, MouseButton, MouseEvent};
 use std::cell::RefCell;
@@ -6,6 +5,7 @@ use std::rc::Rc;
 use theme::ColorStyle;
 use vec::Vec2;
 use view::View;
+use {Printer, With};
 
 struct SharedState<T> {
     selection: usize,
@@ -52,7 +52,7 @@ impl<T> RadioGroup<T> {
     ///
     /// The button will display `label` next to it, and will embed `value`.
     pub fn button<S: Into<String>>(
-        &mut self, value: T, label: S
+        &mut self, value: T, label: S,
     ) -> RadioButton<T> {
         let count = self.state.borrow().values.len();
         self.state.borrow_mut().values.push(Rc::new(value));
@@ -75,7 +75,7 @@ impl<T> RadioGroup<T> {
 impl RadioGroup<String> {
     /// Adds a button, using the label itself as value.
     pub fn button_str<S: Into<String>>(
-        &mut self, text: S
+        &mut self, text: S,
     ) -> RadioButton<String> {
         let text = text.into();
         self.button(text.clone(), text)
@@ -104,7 +104,7 @@ impl<T> RadioButton<T> {
     impl_enabled!(self.enabled);
 
     fn new(
-        state: Rc<RefCell<SharedState<T>>>, id: usize, label: String
+        state: Rc<RefCell<SharedState<T>>>, id: usize, label: String,
     ) -> Self {
         RadioButton {
             state,

src/views/scroll_view.rs

@@ -0,0 +1,530 @@
+use direction::{Direction, Orientation};
+use event::{AnyCb, Event, EventResult, Key, MouseButton, MouseEvent};
+use rect::Rect;
+use theme::ColorStyle;
+use vec::Vec2;
+use view::{Selector, View};
+use xy::XY;
+use Printer;
+use With;
+
+use std::cmp::min;
+
+/// Wraps a view in a scrollable area.
+pub struct ScrollView<V> {
+    // The wrapped view.
+    inner: V,
+
+    // This is the size the child thinks we're giving him.
+    inner_size: Vec2,
+
+    // Offset into the inner view.
+    //
+    // Our `(0,0)` will be inner's `offset`
+    offset: Vec2,
+
+    // What was our own size last time we checked.
+    //
+    // This includes scrollbars, if any.
+    last_size: Vec2,
+
+    // Are we scrollable in each direction?
+    enabled: XY<bool>,
+
+    // Should we show scrollbars?
+    //
+    // Even if this is true, no scrollbar will be printed if we don't need to
+    // scroll.
+    //
+    // TODO: have an option to always show the scrollbar.
+    // TODO: have an option to show scrollbar on top/left.
+    show_scrollbars: bool,
+
+    // How much padding should be between content and scrollbar?
+    scrollbar_padding: Vec2,
+
+    /// Initial position of the cursor when dragging.
+    thumb_grab: Option<(Orientation, usize)>,
+}
+
+impl<V> ScrollView<V> {
+    /// Creates a new ScrollView around `view`.
+    pub fn new(view: V) -> Self {
+        ScrollView {
+            inner: view,
+            inner_size: Vec2::zero(),
+            offset: Vec2::zero(),
+            last_size: Vec2::zero(),
+            enabled: XY::new(false, true),
+            show_scrollbars: true,
+            scrollbar_padding: Vec2::new(1, 0),
+            thumb_grab: None,
+        }
+    }
+
+    /// Returns the viewport in the inner content.
+    pub fn content_viewport(&self) -> Rect {
+        Rect::from_size(self.offset, self.available_size())
+    }
+
+    /// Sets the scroll offset to the given value
+    pub fn set_offset<S>(&mut self, offset: S)
+    where
+        S: Into<Vec2>,
+    {
+        let max_offset = self.inner_size.saturating_sub(self.available_size());
+        self.offset = offset.into().or_min(max_offset);
+    }
+
+    /// Controls whether this view can scroll vertically.
+    ///
+    /// Defaults to `true`.
+    pub fn set_scroll_y(&mut self, enabled: bool) {
+        self.enabled.y = enabled;
+    }
+
+    /// Controls whether this view can scroll horizontally.
+    ///
+    /// Defaults to `false`.
+    pub fn set_scroll_x(&mut self, enabled: bool) {
+        self.enabled.x = enabled;
+    }
+
+    /// Controls whether this view can scroll vertically.
+    ///
+    /// Defaults to `true`.
+    ///
+    /// Chainable variant.
+    pub fn scroll_y(self, enabled: bool) -> Self {
+        self.with(|s| s.set_scroll_y(enabled))
+    }
+
+    /// Controls whether this view can scroll horizontally.
+    ///
+    /// Defaults to `false`.
+    ///
+    /// Chainable variant.
+    pub fn scroll_x(self, enabled: bool) -> Self {
+        self.with(|s| s.set_scroll_x(enabled))
+    }
+    
+    /// Programmatically scroll to the top of the view.
+    pub fn scroll_to_top(&mut self) {
+        let curr_x = self.offset.x;
+        self.set_offset((curr_x,0));   
+    }
+    
+    /// Programmatically scroll to the bottom of the view.
+    pub fn scroll_to_bottom(&mut self) {
+        let max_y = self.inner_size.saturating_sub(self.available_size()).y;
+        let curr_x = self.offset.x; 
+        self.set_offset((curr_x, max_y));
+    }
+    
+    /// Programmatically scroll to the leftmost side of the view.
+    pub fn scroll_to_left(&mut self) {
+        let curr_y = self.offset.y;
+        self.set_offset((0, curr_y));
+    }
+    
+    /// Programmatically scroll to the rightmost side of the view.
+    pub fn scroll_to_right(&mut self) {
+        let max_x = self.inner_size.saturating_sub(self.available_size()).x;
+        let curr_y = self.offset.y;
+        self.set_offset((max_x, curr_y));
+    }
+
+    /// Returns for each axis if we are scrolling.
+    fn is_scrolling(&self) -> XY<bool> {
+        self.inner_size.zip_map(self.last_size, |i, s| i > s)
+    }
+
+    /// Stops grabbing the scrollbar.
+    fn release_grab(&mut self) {
+        self.thumb_grab = None;
+    }
+
+    /// Returns the size taken by the scrollbars.
+    ///
+    /// Will be zero in axis where we're not scrolling.
+    fn scrollbar_size(&self) -> Vec2 {
+        self.is_scrolling()
+            .select_or(self.scrollbar_padding + (1, 1), Vec2::zero())
+    }
+
+    /// Returns the size available for the child view.
+    fn available_size(&self) -> Vec2 {
+        self.last_size.saturating_sub(self.scrollbar_size())
+    }
+}
+
+impl<V> ScrollView<V>
+where
+    V: View,
+{
+    /// Compute the size we would need.
+    ///
+    /// Given the constraints, and the axis that need scrollbars.
+    ///
+    /// Returns `(inner_size, size, scrollable)`.
+    fn sizes_when_scrolling(
+        &mut self, constraint: Vec2, scrollable: XY<bool>,
+    ) -> (Vec2, Vec2, XY<bool>) {
+        // This is the size taken by the scrollbars.
+        let scrollbar_size = scrollable
+            .select_or(self.scrollbar_padding + (1, 1), Vec2::zero());
+
+        let available = constraint.saturating_sub(scrollbar_size);
+
+        // This the ideal size for the child. May not be what he gets.
+        let inner_size = self.inner.required_size(available);
+
+        // Where we're "enabled", accept the constraints.
+        // Where we're not, just forward inner_size.
+        let size = self.enabled.select_or(
+            Vec2::min(inner_size + scrollbar_size, constraint),
+            inner_size + scrollbar_size,
+        );
+
+        // On non-scrolling axis, give inner_size the available space instead.
+        let inner_size = self
+            .enabled
+            .select_or(inner_size, size.saturating_sub(scrollbar_size));
+
+        let new_scrollable = inner_size.zip_map(size, |i, s| i > s);
+
+        (inner_size, size, new_scrollable)
+    }
+
+    /// Starts scrolling from the cursor position.
+    ///
+    /// Returns `true` if the event was consumed.
+    fn start_drag(&mut self, position: Vec2) -> bool {
+        let scrollbar_pos = self.last_size.saturating_sub((1, 1));
+
+        let grabbed = scrollbar_pos.zip_map(position, |s, p| s == p);
+
+        let lengths = self.scrollbar_thumb_lengths();
+        let offsets = self.scrollbar_thumb_offsets(lengths);
+
+        // See if we grabbed one of the scrollbars
+        for (orientation, pos, length, offset) in
+            XY::zip4(Orientation::pair(), position, lengths, offsets)
+                .zip(grabbed.swap())
+                .into_iter()
+                .filter(|&(_, grab)| grab)
+                .map(|(x, _)| x)
+        {
+            if pos >= offset && pos < offset + length {
+                // We grabbed the thumb! Now scroll from that position.
+                self.thumb_grab = Some((orientation, pos - offset));
+            } else {
+                // We hit the scrollbar, outside of the thumb.
+                // Let's move the middle there.
+                self.thumb_grab = Some((orientation, (length - 1) / 2));
+                self.drag(position);
+            }
+
+            return true;
+        }
+
+        false
+    }
+
+    fn drag(&mut self, position: Vec2) {
+        if let Some((orientation, grab)) = self.thumb_grab {
+            self.scroll_to_thumb(
+                orientation,
+                position.get(orientation).saturating_sub(grab),
+            );
+        }
+    }
+
+    fn scroll_to_thumb(&mut self, orientation: Orientation, thumb_pos: usize) {
+        let lengths = self.scrollbar_thumb_lengths();
+        let available = self.available_size();
+
+        // The new offset is:
+        // thumb_pos * (content + 1 - available) / (available + 1 - thumb size)
+        let new_offset = (self.inner_size + (1, 1)).saturating_sub(available)
+            * thumb_pos
+            / (available + (1, 1)).saturating_sub(lengths);
+        let max_offset = self.inner_size.saturating_sub(self.available_size());
+        self.offset
+            .set_axis_from(orientation, &new_offset.or_min(max_offset));
+    }
+
+    /// Computes the size we would need given the constraints.
+    ///
+    /// First be optimistic and try without scrollbars.
+    /// Then try with scrollbars if needed.
+    /// Then try again in case we now need to scroll both ways (!!!)
+    ///
+    /// Returns `(inner_size, size)`
+    fn sizes(&mut self, constraint: Vec2) -> (Vec2, Vec2) {
+        let (inner_size, size, scrollable) =
+            self.sizes_when_scrolling(constraint, XY::new(false, false));
+
+        // If we need to add scrollbars, the available size will change.
+        if scrollable.any() && self.show_scrollbars {
+            // Attempt 2: he wants to scroll? Sure!
+            // Try again with some space for the scrollbar.
+            let (inner_size, size, new_scrollable) =
+                self.sizes_when_scrolling(constraint, scrollable);
+            if scrollable != new_scrollable {
+                // Again? We're now scrolling in a new direction?
+                // There is no end to this!
+                let (inner_size, size, _) =
+                    self.sizes_when_scrolling(constraint, new_scrollable);
+
+                // That's enough. If the inner view changed again, ignore it!
+                // That'll teach it.
+                (inner_size, size)
+            } else {
+                // Yup, scrolling did it. We're goot to go now.
+                (inner_size, size)
+            }
+        } else {
+            // We're not showing any scrollbar, either because we don't scroll
+            // or because scrollbars are hidden.
+            (inner_size, size)
+        }
+    }
+
+    fn scrollbar_thumb_lengths(&self) -> Vec2 {
+        let available = self.available_size();
+        (available * available / self.inner_size).or_max((1, 1))
+    }
+
+    fn scrollbar_thumb_offsets(&self, lengths: Vec2) -> Vec2 {
+        let available = self.available_size();
+        // The number of steps is 1 + the "extra space"
+        let steps = (available + (1, 1)).saturating_sub(lengths);
+        steps * self.offset / (self.inner_size + (1, 1) - available)
+    }
+}
+
+impl<V> View for ScrollView<V>
+where
+    V: View,
+{
+    fn draw(&self, printer: &Printer) {
+        // Draw scrollbar?
+        let scrolling = self.is_scrolling();
+
+        let lengths = self.scrollbar_thumb_lengths();
+        let offsets = self.scrollbar_thumb_offsets(lengths);
+
+        let line_c = XY::new("-", "|");
+
+        let color = if printer.focused {
+            ColorStyle::highlight()
+        } else {
+            ColorStyle::highlight_inactive()
+        };
+
+        let size = self.available_size();
+
+        // TODO: use a more generic zip_all or something?
+        XY::zip5(lengths, offsets, size, line_c, Orientation::pair()).run_if(
+            scrolling,
+            |(length, offset, size, c, orientation)| {
+                let start = printer
+                    .size
+                    .saturating_sub((1, 1))
+                    .with_axis(orientation, 0);
+                let offset = orientation.make_vec(offset, 0);
+
+                printer.print_line(orientation, start, size, c);
+
+                let thumb_c = if self
+                    .thumb_grab
+                    .map(|(o, _)| o == orientation)
+                    .unwrap_or(false)
+                {
+                    " "
+                } else {
+                    "▒"
+                };
+                printer.with_color(color, |printer| {
+                    printer.print_line(
+                        orientation,
+                        start + offset,
+                        length,
+                        thumb_c,
+                    );
+                });
+            },
+        );
+
+        if scrolling.both() {
+            printer.print(printer.size.saturating_sub((1, 1)), "╳");
+        }
+
+        // Draw content
+        let printer = printer
+            .cropped(size)
+            .content_offset(self.offset)
+            .inner_size(self.inner_size);
+        self.inner.draw(&printer);
+    }
+
+    fn on_event(&mut self, event: Event) -> EventResult {
+        // Relativize event accorging to the offset
+        let mut relative_event = event.clone();
+        // eprintln!("Mouse = {:?}", relative_event);
+        if let Some(pos) = relative_event.mouse_position_mut() {
+            *pos = *pos + self.offset;
+        }
+        match self.inner.on_event(relative_event) {
+            EventResult::Ignored => {
+                // If it's an arrow, try to scroll in the given direction.
+                // If it's a mouse scroll, try to scroll as well.
+                // Also allow Ctrl+arrow to move the view,
+                // but not the selection.
+                match event {
+                    Event::Mouse {
+                        event: MouseEvent::WheelUp,
+                        ..
+                    } if self.enabled.y && self.offset.y > 0 =>
+                    {
+                        self.offset.y = self.offset.y.saturating_sub(3);
+                        EventResult::Consumed(None)
+                    }
+                    Event::Mouse {
+                        event: MouseEvent::WheelDown,
+                        ..
+                    } if self.enabled.y
+                        && (self.offset.y + self.available_size().y
+                            < self.inner_size.y) =>
+                    {
+                        self.offset.y = min(
+                            self.inner_size
+                                .y
+                                .saturating_sub(self.available_size().y),
+                            self.offset.y + 3,
+                        );
+                        EventResult::Consumed(None)
+                    }
+                    Event::Mouse {
+                        event: MouseEvent::Press(MouseButton::Left),
+                        position,
+                        offset,
+                    } if position
+                        .checked_sub(offset)
+                        .map(|position| self.start_drag(position))
+                        .unwrap_or(false) =>
+                    {
+                        EventResult::Consumed(None)
+                    }
+                    Event::Mouse {
+                        event: MouseEvent::Hold(MouseButton::Left),
+                        position,
+                        offset,
+                    } => {
+                        let position = position.saturating_sub(offset);
+                        self.drag(position);
+                        EventResult::Consumed(None)
+                    }
+                    Event::Mouse {
+                        event: MouseEvent::Release(MouseButton::Left),
+                        ..
+                    } => {
+                        self.release_grab();
+                        EventResult::Consumed(None)
+                    }
+                    Event::Ctrl(Key::Up) | Event::Key(Key::Up)
+                        if self.enabled.y && self.offset.y > 0 =>
+                    {
+                        self.offset.y -= 1;
+                        EventResult::Consumed(None)
+                    }
+                    Event::Ctrl(Key::Down) | Event::Key(Key::Down)
+                        if self.enabled.y
+                            && (self.offset.y + self.available_size().y
+                                < self.inner_size.y) =>
+                    {
+                        self.offset.y += 1;
+                        EventResult::Consumed(None)
+                    }
+                    Event::Ctrl(Key::Left) | Event::Key(Key::Left)
+                        if self.enabled.x && self.offset.x > 0 =>
+                    {
+                        self.offset.x -= 1;
+                        EventResult::Consumed(None)
+                    }
+                    Event::Ctrl(Key::Right) | Event::Key(Key::Right)
+                        if self.enabled.x
+                            && (self.offset.x + self.available_size().x
+                                < self.inner_size.x) =>
+                    {
+                        self.offset.x += 1;
+                        EventResult::Consumed(None)
+                    }
+                    _ => EventResult::Ignored,
+                }
+            }
+            other => {
+                // Fix offset?
+                let important = self.inner.important_area(self.inner_size);
+
+                // The furthest top-left we can go
+                let top_left = (important.bottom_right() + (1, 1))
+                    .saturating_sub(self.available_size());
+                // The furthest bottom-right we can go
+                let bottom_right = important.top_left();
+
+                // "top_left < bottom_right" is NOT guaranteed
+                // if the child is larger than the view.
+                let offset_min = Vec2::min(top_left, bottom_right);
+                let offset_max = Vec2::max(top_left, bottom_right);
+
+                self.offset =
+                    self.offset.or_max(offset_min).or_min(offset_max);
+
+                other
+            }
+        }
+    }
+
+    fn layout(&mut self, size: Vec2) {
+        // Size is final now
+        self.last_size = size;
+
+        let (inner_size, _) = self.sizes(size);
+
+        // Ask one more time
+        self.inner_size = inner_size;
+
+        self.inner.layout(self.inner_size);
+
+        // The offset cannot be more than content - available
+        self.offset = self
+            .offset
+            .or_min(inner_size.saturating_sub(self.available_size()));
+    }
+
+    fn needs_relayout(&self) -> bool {
+        self.inner.needs_relayout()
+    }
+
+    fn required_size(&mut self, constraint: Vec2) -> Vec2 {
+        // Attempt 1: try without scrollbars
+        let (_, size) = self.sizes(constraint);
+
+        size
+    }
+
+    fn call_on_any<'a>(&mut self, selector: &Selector, cb: AnyCb<'a>) {
+        self.inner.call_on_any(selector, cb)
+    }
+
+    fn focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
+        self.inner.focus_view(selector)
+    }
+
+    fn take_focus(&mut self, source: Direction) -> bool {
+        let is_scrollable = self.is_scrolling().any();
+        self.inner.take_focus(source) || is_scrollable
+    }
+}

src/views/select_view.rs

@@ -1,10 +1,8 @@
-use Cursive;
-use Printer;
-use With;
 use align::{Align, HAlign, VAlign};
 use direction::Direction;
 use event::{Callback, Event, EventResult, Key, MouseButton, MouseEvent};
 use menu::MenuTree;
+use rect::Rect;
 use std::borrow::Borrow;
 use std::cell::Cell;
 use std::cmp::min;
@@ -14,6 +12,9 @@ use unicode_width::UnicodeWidthStr;
 use vec::Vec2;
 use view::{Position, ScrollBase, View};
 use views::MenuPopup;
+use Cursive;
+use Printer;
+use With;
 
 /// View to select an item among a list.
 ///
@@ -526,7 +527,8 @@ impl<T: 'static> SelectView<T> {
                 // the list when we reach the end.
                 // This is achieved by chaining twice the iterator
                 let iter = self.items.iter().chain(self.items.iter());
-                if let Some((i, _)) = iter.enumerate()
+                if let Some((i, _)) = iter
+                    .enumerate()
                     .skip(self.focus() + 1)
                     .find(|&(_, item)| item.label.starts_with(c))
                 {
@@ -640,7 +642,10 @@ impl SelectView<String> {
     }
 
     /// Convenient method to use the label as value.
-    pub fn insert_item_str<S>(&mut self, index: usize, label: S) where S: Into<String> {
+    pub fn insert_item_str<S>(&mut self, index: usize, label: S)
+    where
+        S: Into<String>,
+    {
         let label = label.into();
         self.insert_item(index, label.clone(), label);
     }
@@ -710,8 +715,7 @@ impl<T: 'static> View for SelectView<T> {
         } else {
             let h = self.items.len();
             let offset = self.align.v.get_offset(h, printer.size.y);
-            let printer =
-                &printer.sub_printer(Vec2::new(0, offset), printer.size, true);
+            let printer = &printer.offset((0, offset));
 
             self.scrollbase.draw(printer, |printer, i| {
                 printer.with_selection(i == self.focus(), |printer| {
@@ -732,7 +736,8 @@ impl<T: 'static> View for SelectView<T> {
         // Items here are not compressible.
         // So no matter what the horizontal requirements are,
         // we'll still return our longest item.
-        let w = self.items
+        let w = self
+            .items
             .iter()
             .map(|item| item.label.width())
             .max()
@@ -772,6 +777,12 @@ impl<T: 'static> View for SelectView<T> {
             self.scrollbase.set_heights(size.y, self.items.len());
         }
     }
+
+    fn important_area(&self, size: Vec2) -> Rect {
+        self.selected_id()
+            .map(|i| Rect::from_size((0, i), (size.x, 1)))
+            .unwrap_or_else(|| Rect::from((0, 0)))
+    }
 }
 
 struct Item<T> {
@@ -782,7 +793,7 @@ struct Item<T> {
 impl<T> Item<T> {
     fn new(label: String, value: T) -> Self {
         Item {
-            label: label,
+            label,
             value: Rc::new(value),
         }
     }

src/views/shadow_view.rs

@@ -1,8 +1,8 @@
-use Printer;
 use event::{Event, EventResult};
 use theme::ColorStyle;
 use vec::Vec2;
 use view::{View, ViewWrapper};
+use Printer;
 
 /// Wrapper view that adds a shadow.
 ///
@@ -17,7 +17,7 @@ impl<T: View> ShadowView<T> {
     /// Wraps the given view.
     pub fn new(view: T) -> Self {
         ShadowView {
-            view: view,
+            view,
             top_padding: true,
             left_padding: true,
         }
@@ -80,7 +80,7 @@ impl<T: View> ViewWrapper for ShadowView<T> {
         // Skip the first row/column
         let offset =
             Vec2::new(self.left_padding as usize, self.top_padding as usize);
-        let printer = &printer.offset(offset, true);
+        let printer = &printer.offset(offset);
         if printer.theme.shadow {
             let h = printer.size.y;
             let w = printer.size.x;
@@ -96,11 +96,7 @@ impl<T: View> ViewWrapper for ShadowView<T> {
         }
 
         // Draw the view background
-        let printer = printer.sub_printer(
-            Vec2::zero(),
-            printer.size.saturating_sub((1, 1)),
-            true,
-        );
+        let printer = printer.shrinked((1, 1));
         self.view.draw(&printer);
     }
 }

src/views/sized_view.rs

@@ -3,18 +3,18 @@ use view::View;
 use view::ViewWrapper;
 
 /// Wrapper around a view that remembers its size.
-pub struct SizedView<T: View> {
+pub struct SizedView<T> {
     /// Wrapped view.
     pub view: T,
     /// Cached size from the last layout() call.
     pub size: Vec2,
 }
 
-impl<T: View> SizedView<T> {
+impl<T> SizedView<T> {
     /// Wraps the given view.
     pub fn new(view: T) -> Self {
         SizedView {
-            view: view,
+            view,
             size: Vec2::zero(),
         }
     }

src/views/slider_view.rs

@@ -1,11 +1,11 @@
-use {Cursive, Printer};
-use With;
 use direction::{Direction, Orientation};
 use event::{Callback, Event, EventResult, Key, MouseButton, MouseEvent};
 use std::rc::Rc;
 use theme::ColorStyle;
 use vec::Vec2;
 use view::View;
+use With;
+use {Cursive, Printer};
 
 /// A horizontal or vertical slider.
 pub struct SliderView {
@@ -24,9 +24,9 @@ impl SliderView {
     /// with one tick per block.
     pub fn new(orientation: Orientation, max_value: usize) -> Self {
         SliderView {
-            orientation: orientation,
+            orientation,
             value: 0,
-            max_value: max_value,
+            max_value,
             on_change: None,
             on_enter: None,
             dragging: false,
@@ -186,10 +186,10 @@ impl View for SliderView {
                 offset,
             } if position.fits_in_rect(offset, self.req_size()) =>
             {
-                position.checked_sub(offset).map(|position| {
+                if let Some(position) = position.checked_sub(offset) {
                     self.dragging = true;
                     self.value = self.orientation.get(&position);
-                });
+                }
                 self.get_change_result()
             }
             Event::Mouse {

src/views/stack_view.rs

@@ -1,14 +1,13 @@
-use Printer;
-use With;
 use direction::Direction;
-use event::{Event, EventResult};
-use std::any::Any;
+use event::{AnyCb, Event, EventResult};
 use std::cell;
 use std::ops::Deref;
 use theme::ColorStyle;
 use vec::Vec2;
 use view::{IntoBoxedView, Offset, Position, Selector, View, ViewWrapper};
 use views::{Layer, ShadowView, ViewBox};
+use Printer;
+use With;
 
 /// Simple stack of views.
 /// Only the top-most view is active and can receive input.
@@ -37,7 +36,7 @@ pub enum LayerPosition {
 
 impl Placement {
     pub fn compute_offset<S, A, P>(
-        &self, size: S, available: A, parent: P
+        &self, size: S, available: A, parent: P,
     ) -> Vec2
     where
         S: Into<Vec2>,
@@ -57,8 +56,10 @@ impl Placement {
 enum ChildWrapper<T: View> {
     // Some views include a shadow around.
     Shadow(ShadowView<Layer<T>>),
+    // Some include a background.
+    Backfilled(Layer<T>),
     // Some views don't (fullscreen views mostly)
-    Plain(Layer<T>),
+    Plain(T),
 }
 
 impl<T: View> ChildWrapper<T> {
@@ -68,7 +69,11 @@ impl<T: View> ChildWrapper<T> {
             ChildWrapper::Shadow(shadow) => {
                 shadow.into_inner().ok().unwrap().into_inner().ok().unwrap()
             }
-            ChildWrapper::Plain(layer) => layer.into_inner().ok().unwrap(),
+            // Layer::into_inner can never fail.
+            ChildWrapper::Backfilled(background) => {
+                background.into_inner().ok().unwrap()
+            }
+            ChildWrapper::Plain(layer) => layer,
         }
     }
 }
@@ -78,7 +83,8 @@ impl<T: View> ChildWrapper<T> {
     pub fn get_inner(&self) -> &View {
         match *self {
             ChildWrapper::Shadow(ref shadow) => shadow.get_inner().get_inner(),
-            ChildWrapper::Plain(ref layer) => layer.get_inner(),
+            ChildWrapper::Backfilled(ref background) => background.get_inner(),
+            ChildWrapper::Plain(ref layer) => layer,
         }
     }
 
@@ -88,7 +94,10 @@ impl<T: View> ChildWrapper<T> {
             ChildWrapper::Shadow(ref mut shadow) => {
                 shadow.get_inner_mut().get_inner_mut()
             }
-            ChildWrapper::Plain(ref mut layer) => layer.get_inner_mut(),
+            ChildWrapper::Backfilled(ref mut background) => {
+                background.get_inner_mut()
+            }
+            ChildWrapper::Plain(ref mut layer) => layer,
         }
     }
 }
@@ -98,6 +107,7 @@ impl<T: View> View for ChildWrapper<T> {
     fn draw(&self, printer: &Printer) {
         match *self {
             ChildWrapper::Shadow(ref v) => v.draw(printer),
+            ChildWrapper::Backfilled(ref v) => v.draw(printer),
             ChildWrapper::Plain(ref v) => v.draw(printer),
         }
     }
@@ -105,6 +115,7 @@ impl<T: View> View for ChildWrapper<T> {
     fn on_event(&mut self, event: Event) -> EventResult {
         match *self {
             ChildWrapper::Shadow(ref mut v) => v.on_event(event),
+            ChildWrapper::Backfilled(ref mut v) => v.on_event(event),
             ChildWrapper::Plain(ref mut v) => v.on_event(event),
         }
     }
@@ -112,6 +123,7 @@ impl<T: View> View for ChildWrapper<T> {
     fn layout(&mut self, size: Vec2) {
         match *self {
             ChildWrapper::Shadow(ref mut v) => v.layout(size),
+            ChildWrapper::Backfilled(ref mut v) => v.layout(size),
             ChildWrapper::Plain(ref mut v) => v.layout(size),
         }
     }
@@ -119,6 +131,7 @@ impl<T: View> View for ChildWrapper<T> {
     fn required_size(&mut self, size: Vec2) -> Vec2 {
         match *self {
             ChildWrapper::Shadow(ref mut v) => v.required_size(size),
+            ChildWrapper::Backfilled(ref mut v) => v.required_size(size),
             ChildWrapper::Plain(ref mut v) => v.required_size(size),
         }
     }
@@ -126,17 +139,19 @@ impl<T: View> View for ChildWrapper<T> {
     fn take_focus(&mut self, source: Direction) -> bool {
         match *self {
             ChildWrapper::Shadow(ref mut v) => v.take_focus(source),
+            ChildWrapper::Backfilled(ref mut v) => v.take_focus(source),
             ChildWrapper::Plain(ref mut v) => v.take_focus(source),
         }
     }
 
-    fn call_on_any<'a>(
-        &mut self, selector: &Selector, callback: Box<FnMut(&mut Any) + 'a>
-    ) {
+    fn call_on_any<'a>(&mut self, selector: &Selector, callback: AnyCb<'a>) {
         match *self {
             ChildWrapper::Shadow(ref mut v) => {
                 v.call_on_any(selector, callback)
             }
+            ChildWrapper::Backfilled(ref mut v) => {
+                v.call_on_any(selector, callback)
+            }
             ChildWrapper::Plain(ref mut v) => {
                 v.call_on_any(selector, callback)
             }
@@ -146,6 +161,7 @@ impl<T: View> View for ChildWrapper<T> {
     fn focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
         match *self {
             ChildWrapper::Shadow(ref mut v) => v.focus_view(selector),
+            ChildWrapper::Backfilled(ref mut v) => v.focus_view(selector),
             ChildWrapper::Plain(ref mut v) => v.focus_view(selector),
         }
     }
@@ -184,7 +200,7 @@ impl StackView {
     {
         let boxed = ViewBox::boxed(view);
         self.layers.push(Child {
-            view: ChildWrapper::Plain(Layer::new(boxed)),
+            view: ChildWrapper::Backfilled(Layer::new(boxed)),
             size: Vec2::zero(),
             placement: Placement::Fullscreen,
             virgin: true,
@@ -270,6 +286,16 @@ impl StackView {
         self.with(|s| s.add_fullscreen_layer(view))
     }
 
+    /// Adds a new transparent layer on top of the stack.
+    ///
+    /// Chainable variant.
+    pub fn transparent_layer<T>(self, view: T) -> Self
+    where
+        T: IntoBoxedView,
+    {
+        self.with(|s| s.add_transparent_layer(view))
+    }
+
     /// Adds a view on top of the stack.
     pub fn add_layer_at<T>(&mut self, position: Position, view: T)
     where
@@ -289,6 +315,28 @@ impl StackView {
         });
     }
 
+    /// Adds a transparent view on top of the stack in the center of the screen.
+    pub fn add_transparent_layer<T>(&mut self, view: T)
+    where
+        T: IntoBoxedView,
+    {
+        self.add_transparent_layer_at(Position::center(), view);
+    }
+
+    /// Adds a transparent view on top of the stack.
+    pub fn add_transparent_layer_at<T>(&mut self, position: Position, view: T)
+    where
+        T: IntoBoxedView,
+    {
+        let boxed = ViewBox::boxed(view);
+        self.layers.push(Child {
+            view: ChildWrapper::Plain(boxed),
+            size: Vec2::new(0, 0),
+            placement: Placement::Floating(position),
+            virgin: true,
+        });
+    }
+
     /// Adds a view on top of the stack.
     ///
     /// Chainable variant.
@@ -364,7 +412,7 @@ impl StackView {
     /// Has no effect on fullscreen layers
     /// Has no effect if layer is not found
     pub fn reposition_layer(
-        &mut self, layer: LayerPosition, position: Position
+        &mut self, layer: LayerPosition, position: Position,
     ) {
         let i = self.get_index(layer);
         let child = match self.layers.get_mut(i) {
@@ -411,11 +459,10 @@ impl StackView {
                 StackPositionIterator::new(self.layers.iter(), printer.size)
                     .enumerate()
             {
-                v.view.draw(&printer.sub_printer(
-                    offset,
-                    v.size,
-                    i + 1 == last,
-                ));
+                v.view.draw(&printer
+                    .offset(offset)
+                    .cropped(v.size)
+                    .focused(i + 1 == last));
             }
         });
     }
@@ -527,8 +574,7 @@ impl View for StackView {
     }
 
     fn call_on_any<'a>(
-        &mut self, selector: &Selector,
-        mut callback: Box<FnMut(&mut Any) + 'a>,
+        &mut self, selector: &Selector, mut callback: AnyCb<'a>,
     ) {
         for layer in &mut self.layers {
             layer
@@ -617,4 +663,52 @@ mod tests {
 
         assert!(stack.pop_layer().is_none());
     }
+
+    #[test]
+    fn get() {
+        let mut stack = StackView::new()
+            .layer(TextView::new("1"))
+            .layer(TextView::new("2"));
+
+        assert!(
+            stack
+                .get(LayerPosition::FromFront(0))
+                .unwrap()
+                .as_any()
+                .downcast_ref::<ViewBox>()
+                .unwrap()
+                .with_view(|v| v.as_any().is::<TextView>())
+                .unwrap()
+        );
+        assert!(
+            stack
+                .get(LayerPosition::FromBack(0))
+                .unwrap()
+                .as_any()
+                .downcast_ref::<ViewBox>()
+                .unwrap()
+                .with_view(|v| v.as_any().is::<TextView>())
+                .unwrap()
+        );
+        assert!(
+            stack
+                .get_mut(LayerPosition::FromFront(0))
+                .unwrap()
+                .as_any_mut()
+                .downcast_mut::<ViewBox>()
+                .unwrap()
+                .with_view_mut(|v| v.as_any_mut().is::<TextView>())
+                .unwrap()
+        );
+        assert!(
+            stack
+                .get_mut(LayerPosition::FromBack(0))
+                .unwrap()
+                .as_any_mut()
+                .downcast_mut::<ViewBox>()
+                .unwrap()
+                .with_view_mut(|v| v.as_any_mut().is::<TextView>())
+                .unwrap()
+        );
+    }
 }

src/views/text_area.rs

@@ -1,6 +1,6 @@
-use {Printer, With, XY};
 use direction::Direction;
 use event::{Event, EventResult, Key, MouseButton, MouseEvent};
+use rect::Rect;
 use std::cmp::min;
 use theme::{ColorStyle, Effect};
 use unicode_segmentation::UnicodeSegmentation;
@@ -8,6 +8,7 @@ use unicode_width::UnicodeWidthStr;
 use utils::lines::simple::{prefix, simple_prefix, LinesIterator, Row};
 use vec::Vec2;
 use view::{ScrollBase, SizeCache, View};
+use {Printer, With, XY};
 
 /// Multi-lines text editor.
 ///
@@ -162,6 +163,10 @@ impl TextArea {
         self.row_at(self.cursor)
     }
 
+    fn selected_col(&self) -> usize {
+        self.col_at(self.cursor)
+    }
+
     fn page_up(&mut self) {
         for _ in 0..5 {
             self.move_up();
@@ -437,7 +442,8 @@ impl View for TextArea {
         debug!("{:?}", self.rows);
         let scroll_width = if self.rows.len() > constraint.y { 1 } else { 0 };
         Vec2::new(
-            scroll_width + 1
+            scroll_width
+                + 1
                 + self.rows.iter().map(|r| r.width).max().unwrap_or(1),
             self.rows.len(),
         )
@@ -568,13 +574,10 @@ impl View for TextArea {
                 event: MouseEvent::Press(_),
                 position,
                 offset,
-            } if position.fits_in_rect(offset, self.last_size) =>
+            } if !self.rows.is_empty()
+                && position.fits_in_rect(offset, self.last_size) =>
             {
-                position.checked_sub(offset).map(|position| {
-                    if self.rows.is_empty() {
-                        return;
-                    }
-
+                if let Some(position) = position.checked_sub(offset) {
                     let y = position.y + self.scrollbase.start_line;
                     let y = min(y, self.rows.len() - 1);
                     let x = position.x;
@@ -582,7 +585,7 @@ impl View for TextArea {
                     let content = &self.content[row.start..row.end];
 
                     self.cursor = row.start + simple_prefix(content, x).length;
-                });
+                }
             }
             _ => return EventResult::Ignored,
         }
@@ -604,4 +607,24 @@ impl View for TextArea {
         self.last_size = size;
         self.compute_rows(size);
     }
+
+    fn important_area(&self, _: Vec2) -> Rect {
+        // The important area is a single character
+        let char_width = if self.cursor >= self.content.len() {
+            // If we're are the end of the content, it'll be a space
+            1
+        } else {
+            // Otherwise it's the selected grapheme
+            self.content[self.cursor..]
+                .graphemes(true)
+                .next()
+                .unwrap()
+                .width()
+        };
+
+        Rect::from_size(
+            (self.selected_col(), self.selected_row()),
+            (char_width, 1),
+        )
+    }
 }

src/views/text_view.rs

@@ -1,19 +1,19 @@
-use Printer;
-use With;
-use XY;
 use align::*;
 use direction::Direction;
 use event::*;
 use owning_ref::{ArcRef, OwningHandle};
 use std::ops::Deref;
-use std::sync::{Mutex, MutexGuard};
 use std::sync::Arc;
+use std::sync::{Mutex, MutexGuard};
 use theme::Effect;
 use unicode_width::UnicodeWidthStr;
 use utils::lines::spans::{LinesIterator, Row};
 use utils::markup::StyledString;
 use vec::Vec2;
 use view::{ScrollBase, ScrollStrategy, SizeCache, View};
+use Printer;
+use With;
+use XY;
 
 /// Provides access to the content of a [`TextView`].
 ///
@@ -421,7 +421,8 @@ impl TextView {
         }
 
         // Desired width, including the scrollbar_width.
-        self.width = self.rows
+        self.width = self
+            .rows
             .iter()
             .map(|row| row.width)
             .max()
@@ -451,7 +452,7 @@ impl View for TextView {
         let h = self.rows.len();
         // If the content is smaller than the view, align it somewhere.
         let offset = self.align.v.get_offset(h, printer.size.y);
-        let printer = &printer.offset((0, offset), true);
+        let printer = &printer.offset((0, offset));
 
         let content = self.content.lock().unwrap();
 

src/views/tracked_view.rs

@@ -1,8 +1,8 @@
-use Printer;
 use std::cell::Cell;
 use vec::Vec2;
 use view::{View, ViewWrapper};
 use views::IdView;
+use Printer;
 
 /// Wrapper around a view that remembers its position.
 pub struct TrackedView<T: View> {
@@ -21,7 +21,7 @@ impl<T: View> TrackedView<T> {
     /// Creates a new `TrackedView` around `view`.
     pub fn new(view: T) -> Self {
         TrackedView {
-            view: view,
+            view,
             offset: Cell::new(Vec2::zero()),
         }
     }

src/xy.rs

@@ -16,18 +16,60 @@ impl<T> XY<T> {
         XY { x, y }
     }
 
+    /// Swaps the x and y values.
+    pub fn swap(self) -> Self {
+        XY::new(self.y, self.x)
+    }
+
+    /// Returns `f(self.x, self.y)`
+    pub fn fold<U, F>(self, f: F) -> U
+    where
+        F: FnOnce(T, T) -> U,
+    {
+        f(self.x, self.y)
+    }
+
     /// Creates a new `XY` by applying `f` to `x` and `y`.
-    pub fn map<U, F: Fn(T) -> U>(self, f: F) -> XY<U> {
+    pub fn map<U, F>(self, f: F) -> XY<U>
+    where
+        F: Fn(T) -> U,
+    {
         XY::new(f(self.x), f(self.y))
     }
 
+    /// Applies `f` on axis where `condition` is true.
+    ///
+    /// Carries over `self` otherwise.
+    pub fn map_if<F>(self, condition: XY<bool>, f: F) -> Self
+    where
+        F: Fn(T) -> T,
+    {
+        self.zip_map(condition, |v, c| if c { f(v) } else { v })
+    }
+
+    /// Applies `f` on axis where `condition` is true.
+    ///
+    /// Returns `None` otherwise.
+    pub fn run_if<F, U>(self, condition: XY<bool>, f: F) -> XY<Option<U>>
+    where
+        F: Fn(T) -> U,
+    {
+        self.zip_map(condition, |v, c| if c { Some(f(v)) } else { None })
+    }
+
     /// Creates a new `XY` by applying `f` to `x`, and carrying `y` over.
-    pub fn map_x<F: Fn(T) -> T>(self, f: F) -> Self {
+    pub fn map_x<F>(self, f: F) -> Self
+    where
+        F: FnOnce(T) -> T,
+    {
         XY::new(f(self.x), self.y)
     }
 
     /// Creates a new `XY` by applying `f` to `y`, and carrying `x` over.
-    pub fn map_y<F: Fn(T) -> T>(self, f: F) -> Self {
+    pub fn map_y<F>(self, f: F) -> Self
+    where
+        F: FnOnce(T) -> T,
+    {
         XY::new(self.x, f(self.y))
     }
 
@@ -46,6 +88,11 @@ impl<T> XY<T> {
         iter::once(&self.x).chain(iter::once(&self.y))
     }
 
+    /// Creates an iterator that returns `x`, then `y`.
+    pub fn into_iter(self) -> iter::Chain<iter::Once<T>, iter::Once<T>> {
+        iter::once(self.x).chain(iter::once(self.y))
+    }
+
     /// Returns a reference to the value on the given axis.
     pub fn get(&self, o: Orientation) -> &T {
         match o {
@@ -67,8 +114,30 @@ impl<T> XY<T> {
         XY::new((self.x, other.x), (self.y, other.y))
     }
 
+    /// Returns a new `XY` of tuples made by zipping `self`, `a` and `b`.
+    pub fn zip3<U, V>(self, a: XY<U>, b: XY<V>) -> XY<(T, U, V)> {
+        XY::new((self.x, a.x, b.x), (self.y, a.y, b.y))
+    }
+
+    /// Returns a new `XY` of tuples made by zipping `self`, `a`, `b` and `c`.
+    pub fn zip4<U, V, W>(
+        self, a: XY<U>, b: XY<V>, c: XY<W>,
+    ) -> XY<(T, U, V, W)> {
+        XY::new((self.x, a.x, b.x, c.x), (self.y, a.y, b.y, c.y))
+    }
+
+    /// Returns a new `XY` of tuples made by zipping `self`, `a`, `b`, `c` and `d`.
+    pub fn zip5<U, V, W, Z>(
+        self, a: XY<U>, b: XY<V>, c: XY<W>, d: XY<Z>,
+    ) -> XY<(T, U, V, W, Z)> {
+        XY::new((self.x, a.x, b.x, c.x, d.x), (self.y, a.y, b.y, c.y, d.y))
+    }
+
     /// Returns a new `XY` by calling `f` on `self` and `other` for each axis.
-    pub fn zip_map<U, V, F: Fn(T, U) -> V>(self, other: XY<U>, f: F) -> XY<V> {
+    pub fn zip_map<U, V, F>(self, other: XY<U>, f: F) -> XY<V>
+    where
+        F: Fn(T, U) -> V,
+    {
         XY::new(f(self.x, other.x), f(self.y, other.y))
     }
 }
@@ -97,19 +166,31 @@ impl<T: Clone> XY<T> {
 impl<T> XY<Option<T>> {
     /// Returns a new `XY` by calling `unwrap_or` on each axis.
     pub fn unwrap_or(self, other: XY<T>) -> XY<T> {
-        self.zip_map(other, |s, o| s.unwrap_or(o))
+        self.zip_map(other, Option::unwrap_or)
     }
 }
 
 impl XY<bool> {
     /// Returns `true` if any of `x` or `y` is `true`.
     pub fn any(&self) -> bool {
-        self.x || self.y
+        use std::ops::BitOr;
+        self.fold(BitOr::bitor)
     }
 
     /// Returns `true` if both `x` and `y` are `true`.
     pub fn both(&self) -> bool {
-        self.x && self.y
+        use std::ops::BitAnd;
+        self.fold(BitAnd::bitand)
+    }
+
+    /// For each axis, keeps elements from `other` if `self` is `true`.
+    pub fn select<T>(&self, other: XY<T>) -> XY<Option<T>> {
+        self.zip_map(other, |keep, o| if keep { Some(o) } else { None })
+    }
+
+    /// For each axis, selects `if_true` if `self` is true, else `if_false`.
+    pub fn select_or<T>(&self, if_true: XY<T>, if_false: XY<T>) -> XY<T> {
+        self.select(if_true).unwrap_or(if_false)
     }
 }
 
@@ -125,3 +206,9 @@ impl<T> From<(T, T)> for XY<T> {
         XY::new(x, y)
     }
 }
+
+impl<T, U> From<(XY<T>, XY<U>)> for XY<(T, U)> {
+    fn from((t, u): (XY<T>, XY<U>)) -> Self {
+        t.zip(u)
+    }
+}