Wouldn't it be great to allow applications to use keyboard shortcuts for elemnts of a GtkComboBox? I don't know how such a thing normally works, but I suppose the application should handle the key-to-action binding, since focus might be somewhere other than on the combobox. Then what's left for GtkComboBox is to allow some way of indicating to the user that shortcuts exist and what keys to press.
It could work like in menus with right-aligned strings like "Ctrl+C". A different standard (using the Alt-key) is to underline (up to) one character at each line, and let Alt+[that character] be the shortcut.
I guess then GtkComboBox only need support for setting which letter to underline, or key sequence to display for each item in the list. The default should of course be to not display any such shortcut.
If the common practice is to let the control/widget itself handle key bindigs to shortcuts then this too would of course be made to work in the same way, but for the case I'm thinking of (http://bugzilla.gnome.org/show_bug.cgi?id=425258) I want shortcuts to work without focus on the related GtkComboBox.