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From: msc@ramoth.esd.sgi.com (Mark Callow)
Newsgroups: comp.windows.news
Subject: Re: Flickering canvases
Keywords: moving canvas flickering
Message-ID: <1272@odin.SGI.COM>
Date: 6 Nov 89 19:10:55 GMT
References: <1989Nov6.111754.11056@m2cs.uu.no>
Sender: news@odin.SGI.COM
Reply-To: msc@ramoth.esd.sgi.com (Mark Callow)
Organization: Silicon Graphics Inc., Entry Systems Division
Lines: 24

In article <1989Nov6.111754.11056@m2cs.uu.no>, tomas@m2cs.uu.no (Tomas
Felner) writes:
> I have a problem with moving canvases that has been bothering me for
> quite some time. The basic situation is as follows: I have a canvas
> ontop of which I have another canvas, on top of which another one, etc. I
> have code to grab one of those canvases with the mouse and move them around.
> All the canvases on top of the grabbed canvas are then moved together
> with the grabbed one. When moving this "stack of canvases" the moving of 
> the bottommost canvas goes smoothly, but all the canvases on top of it
> flicker like crazy! This effect appears with any stack of canvases and 
> with an arbitray number of canvases on top of the bottom canvas.
You don't say what version of NeWS you are running...

In NeWS 1.1 (and 4Sight) when you move a canvas containing opaque children,
the opaque children are unmapped while the canvas is moved then remapped. 
This may be the cause of your flickering.  The unmapping was done to ensure
that some obscure case involving retained canvases and save unders would
work correctly.  I believe Sun found this to be unnecessary so NeWS 2.0
(X11/NeWS) doesn't unmap the canvases anymore. 
--
From the TARDIS of Mark Callow
msc@ramoth.sgi.com, ...{ames,decwrl}!sgi!msc
"There is much virtue in a window.  It is to a human being as a frame is to
a painting, as a proscenium to a play.  It strongly defines its content."