Press key to modify UI

[Tobias Weber <towb celvina de>]

Hi,
on the Mac rarely needed functionality is often hidden. If you open a menu or dialog and then hold down the 
ALT key, some items and buttons will change their label. Clicking with the key down triggers something 
different than without.

I found it hard to do that with GTK. Modifiers aren't part of signals like "clicked". What do I do if a 
focussed Entry hogs all key-press-events?

Maybe I shouldn't try because no Gnome user will expect this? But how to unclutter my interface? I've seen 
applications having context menus everywhere, but that's not as discoverable.