* Added Ctrl+Z to the Keyboard Shortcuts dialog.
* Added Arrow Keys and Shift + Arrow Keys shortcuts to the Keyboard Shortcuts dialog.
* Added the [Backspace] key to the Keyboard Shortcuts dialog.
This gets rid of the need to enable/disable the keyboard handling
at various times.
Allows Ctrl-C to work as expected when selecting text in debug/info
sidebar.
Downside is shortcuts that apply to the workspace (select-all, copy
etc) now require the workspace to be focussed.