Using modifier keys other than control in custom keybindings

[Samir Unni]

Hi,

I'm trying to figure out how to set a keybinding for "switch the input focus to the previous region" as C-a shift-tab. However, the "Default Key Bindings" section on the man page doesn't show any examples of the syntax for using modifier keys other than control that I can base my custom key binding off of. So I have 2 questions about custom keybindings:

1. Is "switch the input focus to the previous region" a possible action to bind a key to? I'm using the CVS version of screen, and due to the support for vertical splitting, I frequently end up with 4 or 5 terminals in one screen session. It's very frustrating to have to C-a tab 3 or 4 times to get to the previous terminal, when I'm switching between two of those 4 or 5 terminals a lot in a short period of time.
2. Is it even possible to set a key binding with a modifier key other than control?

Thanks!