Detecting popup menu cancelation

[Jeffrey Massung]

I have a popup button that, when clicked, I change the background color of a field so as to really highlight for the user exactly what their action is going to be taken on.

However, currently, I have no way of detecting if the user chooses to do nothing (cancel the popup) and subsequently return the field's background color to its default.

Is there some message I can key off of or some other way for me to accomplish this behavior?

Thanks!

Jeff M.