There is a way to add a "dirty listener". so if they change a field but don't save it you'll get a popup telling you before you exit.
Is that what you're looking for?
I've used it once in XPiNC - but I don't have that code handy. I think there's something in All Properties... There's also a mention of it on Stephan's blog..
http://www.wissel.net/blog/d6plinks/SHWL-878B9D