As I was typing my reply, I had that same thought, even the part about that's not what I wanted to hear! :) I think that is where I'm headed, but I did find that I could put this code in my Application Close button:

IF !EMPTY(WONTOP())
    * There is a form open here, since I have a master form that is always opened this should always return
    * something.  But it is blank if the report preview window is open.
    Do oApp.CloseApp
else
    * Skip shutdown, the Report Preview seems to be open
endif