How can I open a menu from the root window using PyGTK?

I want to open a menu without a window, bar, status icon, etc, only on the root window, like the menu of openbox or something like this http://img404.imageshack.us/img404/7189/2010120112912208781680xx.png, that is a menu made it with pygtk but he 开发者_运维技巧never made it public, i want make something like that but i dont have a idea how open a menu on the root window using pygtk. If some one can give me some feedback i'll be grateful.

My english is horrible, so, sorry :P