Variable pixmap/name in a Button or Variable Toolbar?

["Dr. Chiarello Davide" <ovichi tin it>]

Which is the easiest way to change the pixmap or the name/label of some
buttons in a toolbar?

I've just created it with glade... i need to change the functions/aspect
of the toolbar buttons by selecting an item from a menu.

Is possible to destroy the old one and replace it with a new one?
(Yes I'm at the very 1st steps : excuse me)
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