wxPython and EVT_UPDATE_UI

[Jonathan M. Gilligan]

I am trying to implement checked menu items like radio buttons (only one of
four menu items can be  checked at a time). I tried using
EVT_UPDATE_UI(<window>,<id>,<function>), in the same way that the demos use
EVT_MENU(), but my callback functions for EVT_UPDATE_UI never get called.

Can anyone explain how to use EVT_UPDATE_UI() properly to update a menu item
in wxPython (or suggest another way to solve this problem)?

Thanks,
Jonathan