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From: keithd@cadovax.UUCP (Keith Doyle)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga Screen Bug
Message-ID: <1809@cadovax.UUCP>
Date: Fri, 16-Oct-87 14:20:05 EDT
Article-I.D.: cadovax.1809
Posted: Fri Oct 16 14:20:05 1987
Date-Received: Sun, 18-Oct-87 08:33:19 EDT
References: <1636@mit-amt.MEDIA.MIT.EDU>
Reply-To: keithd@cadovax.UUCP (Keith Doyle)
Distribution: na
Organization: Contel Business Systems, Torrance, CA
Lines: 50

In article <1636@mit-amt.MEDIA.MIT.EDU> ralph@mit-atrp.UUCP (Amiga-Man) writes:
>I'm working with, lets say AegisDrawPlus, uEmacs, popCLI,
>performance monitor, and the workbench (I have 2.5Meg on a A1000).
>Now, I pop the uEmacs screen forward, do a little text action, then pop
>it to the back. The highres DrawPlus screen come forward as only it's upper
>half, displayed in non-interlace (200lines). It looks like the screen
>information got walked on.

I've seen exactly this effect, when using a lo-res screen that has been
modified to a high res screen by modifying the view and viewport
structures, and doing a MakeView MrgCop LoadView etc.  The information
has not been walked on, somehow intuition seems to be confused as to
just how many lines are supposed to be on screen.  If the hi-res
application later does another LoadView etc., the lower part of the
screen will come back intact.

I also found that if you go to the workbench and drag the workbench screen
down in front of the hi-res screen, similar effects would occur.

>If, I only use left-amiga-N to bring the workbench forward everything
>lives and keeps running. BUT, if I try to use the mouse to push this
>broken screen back, lockup&reboot.

Haven't tried this, I was using a screen that didn't have a screen-to-back
gadget.

>The really bad news is that I've seen this with several different programs,
>And also without any uEmacs running.
>It almost seems like it's a bug in intuition, since it appears independent
>of the exact programs. It seems to be correlated with poping between interlace
>and non-interlace screens. If I'm not alone on this, maybe I'll try to get
>a specific reproduction of the setup and operations which cause it
>reliably. It is a major problem, and makes it hard to depend on the machine
>(which I really do depend on these days).

As I've said, it's happened to me.  Unfortunately, what I'm doing is not 
exactly a Commodore approved mechanism for changing the resolution of a screen
(is there one? as far as I know, no.) so CATS might just say it's
not a bug but a feature.  However, it seems that maybe the problem
is that I somehow need to tell Intuition that the screen resolution has
been modified, and if that is doable, it implies the bug is in DrawPlus and
not in Intuition.  

Let me know what you find out.  With my program, the problem is not at
all critical, because it dosen't hang (no screen-to-back gadget) and it
does its own LoadView etc. often enough to cure itself pretty quick.
Still, if I knew what to do to fix it I certainly would.

Keith Doyle
#  {ucbvax,decvax}!trwrb!cadovax!keithd  Contel Business Systems 213-323-8170