Application in front?

Is there a simple way to see if my app is the current front (i.e. should handle user input, and be allowed to reposition the mouse) app, or not? On windows if something pops up, or you hit the windows key to open the start menu etc. and my app goes into the background it remains in control of the mouse, re-centering it every frame, this is obivously not so good... but I can't figure out a way to tell when it looses focus.

check for the EVENT_APPSUSPEND
or use the app suspended function

AppSuspended() perfect!