Combo box event question

[bjohns44 csc com au]

I did a quick search through the archives and could find nothing on [combo*
and event] so I was hoping that someone on the list may know.
The question:
     Is there an event for the combo box that gets fired when a selection
has been made?
There seems to be no obvious choice. Even used Glade to check events on
combo to see if anything stood out.
My idea:
     I need an event to be fired off when something is selected. ( ie. when
dropdown list is in play and one of the choices is clicked an after that
click the window is closed ) Is there any event in there like delete_event
for the pop-down window that I could use for something like an after_update
event?

Any ideas?
Brandon Johnson
Systems Engineer - NES
CSC Whyalla
ph: +61-8-8640-4530