Careful: Ctrl-4 and ctrl-\ currently make ncurses crash.
Also some letters combine with Ctrl to make other codes. Run stty -a to
see some mappings.
Basically, you'll have issues with:
C,I,J,M,Q,S,Z
and non-letters.
Callbacks now include a path to the triggering view.
The Cursive root can find the View corresponding to a ViewPath.
In the future, ViewPaths may be returned when creating the layout.