GtkToolItem custom widget - hybrid of GtkRadioToolButton and GtkMenuToolButton

[Dov Grobgeld <dov grobgeld gmail com>]

Hello,

I'm working on a space challenged device (Nokia N900) and in order to save space I would like to create a hybrid of a GtkToolbar (that will be shown at the bottom of the screen, and hidden when not in use) with the following properties:

• There should be several GtkRadioToolButton groups.
• If a GtkRadioToolButton is selected and receives a second clicked then a menu should be popped up.
• The popped up menu should be a (perpendicular) GtkToolBar (or perhaps a GtkMenu with RadioButton?)
• The menu is popped down after a selection is made in it (like a normal menu).
  

My question is if such a widget already exists, and if not what would be good choices to use as base widgets for the different widget components that I mentioned above (the button and the menu)?

Thanks!
Dov