How to put a pixmap on a GtkMenuItem?

[<hunchback netcabo pt>]

Hi,

I'm trying to do a Menu Bar, which, contains GtkMenu... I'm trying to put
a pixmap and a label, instead of just a label on the items of the menu.. 
i tried all i can think of, but he complains allways that the item isn't a
GtkMenuItem... (an assertion of the GtkMenuShell, i think..) 
How do i put a pixmap and a label on a GtkMenuItem?

Thanks for any help,
Afonso