[RBG7-L] - Detecting Close Button [X]

[Doug Hamilton]

How do I tell if the Close Button, [X] in the upper right corner, has 
been clicked?
I need to detect it so I can close the app.  I've got a "Quit" button 
that works ok,
but client wants the same results from the Close button.
Is it an RBTI_Form var?  Some other var?

TIA
Doug