Tkinter events - how to make a "change" event?

[Thomas Lane]

I'm using a Pmw.ComboBox and I want to handle a "change" event for the
text field. First of all, callbacks bound to a Pmw.ComboBox don't seem
to work. I can bind them, but the functions never get called. Does
anyone know why? Second, from what I've read, it looks like Tkinter only
supports mouse and keyboard events, so there is no such thing as a
"change" event. What is the best way to implement something like this?
Should I just catch every mouse and keyboard event for the object and
check for a change every time? Any help would be appreciated.

-Tom
tom at parlant.com