#3 CTRL-Tab does not work

[John Gallardo]

CTRL-Tab normally switches between tabs in a tab
display (see Visual Studio.NET). Here it doesn't work.

Repro:
1.) Open SharpEdit
2.) Open some files or create new buffers
3.) Press CTRL-Tab

Actual Outcome:
Nothing

Expected Outcome:
Should switch between windows. Switching works the
way ALT-Tab works in windows, using some sort of
LIFO data structure so you switch to buffers in order of
most-recently-used.