combo box activation

[Marc Ewing <marc redhat com>]

I have a combo box.  I'm trying to get a function to be called when
either "Return" is pressed inside the entry widget, or when an item is
selected from the combo box menu.

I tried connecting to both the entry "set_text" and "activate",
but this results in multiple invocations of my function (four,
I think) - I just want one.  Just connecting to "activate" means
the user has to press "Return" after selecting from the menu.

Is there a good way to do this?

Thanks,
Marc