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From: rowley@ORVILLE.ARPA (Karl Rowley)
Newsgroups: comp.sys.atari.st
Subject: Re: Re: AES bug
Message-ID: <8708061855.AA25677@orville.arpa>
Date: Thu, 6-Aug-87 14:55:18 EDT
Article-I.D.: orville.8708061855.AA25677
Posted: Thu Aug  6 14:55:18 1987
Date-Received: Sat, 8-Aug-87 12:00:32 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 36

In article <2233@ihuxz.ATT.COM>  burris@ihuxz.ATT.COM (Burris) writes:
>
>Do you know if the applications you are running are using the wind_update()
>routine before doing any drawing inside a window?

Yes, I have seen this problem when the application and desk accessories running
(which I had written) were all using wind_update correctly.  The problem I was
referring to is not that windows get trashed when they are updated.  The 
problem is with windows that the screen manager thinks still exist, but should
not exist.

If you have the Mark Williams C package, you can recreate the problem as
follows:
1) Run the msh shell.
2) From msh start GEM kermit (or another GEM program that lets you use desk
	accessories).
3) Open the Control Panel from inside of kermit.
4) Exit kermit without closing the Control Panel.
5) Run kermit again from msh.
6) Open the Control Panel again.  Move it all around the screen.  Notice how
	the screen manager still thinks there is a second window titled
	"Control Panel"?  The second window is never redrawn, but fills up
	with garbage as the other window is moved around over it.  If steps
	4, 5, and 6 are repeated again a number of times, there will eventually
	be no window handles left and the Control Panel will not open when
	selected.
7) Go back to the desktop.  Repeat steps 3-6 running kermit from the desktop.
	Everything looks fine.

My conclusion: the GEM desktop is doing something to close/clean up desk
accessories/windows between running applications.  The msh shell must not.

Does anyone know how the desktop does this?

	Karl Rowley
	rowley@ames-nas.arpa