>OK, now I really DON'T understand. When I removed the
>flushwindowbuffer statements the marquee does not display. I am using
>WHILE FN StillDown : WEND, but still need to use flushwindowbuffer.

It seems that the flushwindowbuffer statement is in the correct place.

http://developer.apple.com/ReleaseNotes/Carbon/RN-HIToolbox/index.html

Tips for Compatibility with Mac OS X 10.4

Window Manager

"The Window Manager on Mac OS X has always flushed the window buffers 
of all visible windows during any call to the event loop, including 
calls to the StillDown, WaitMouseUp, and EventAvail APIs. These APIs 
have historically been fast, light-weight calls, and the addition of 
flushing in the Mac OS X implementation has been considered a 
drawback by some applications. We hope to address this issue in a 
future release of Mac OS X by changing the behavior of these APIs, 
but there is no behavioral change in Mac OS X 10.4. For compatibility 
with future versions of Mac OS X, we recommend that you do not rely 
on StillDown, WaitMouseUp, or EventAvail causing a window flush."

IMPORTANT:

"If your application has a tight loop that calls no event API except 
one of these three, which should be rare in a modern Carbon 
application, you can simply add an explicit call to QDFlushPortBuffer 
to flush the appropriate window."

Which OS are you using? 10.5? PPC or Intel?

Michele.