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From: mouse@lightning.mcrcim.mcgill.EDU
Newsgroups: comp.windows.x
Subject: Re:  PC X servers / backing store
Message-ID: <9103020232.AA05738@lightning.McRCIM.McGill.EDU>
Date: 2 Mar 91 02:32:00 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 22

> The client software I am using is GRAFIT running on an HP 9000/825.

> A problem encountered with both products is that if a graphics window
> is overlaid ( e.g. by a menu ), the overlaid portion is not restored.
> The suppliers of Grafit informed me that the X server implementation
> probably did not support backing store  - a requirement for their
> package ( or for the HP Starbase/X implementation? ).

Then their package is buggy.  X programs must *always* be prepared to
deal with Expose events!  If they *must* have backing-store-style
semantics, then they should arrange their own pseudo-backing-store.
For example, they might create a pixmap and use it to handle exposures.
This is a mildly bad idea (pixmap memory may be a precious resource),
but is certainly a better idea than breaking if the server doesn't
choose to maintain backing-store!

Who are "[t]he suppliers of Grafit"?  I want to know who to avoid....

					der Mouse

			old: mcgill-vision!mouse
			new: mouse@larry.mcrcim.mcgill.edu