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From: msm@src.dec.com (Mark S. Manasse)
Newsgroups: comp.windows.x
Subject: Re: PC X servers / backing store
Message-ID: <1991Mar6.094926.8556@src.dec.com>
Date: 6 Mar 91 17:49:26 GMT
References: <9103060612.AA19880@lightning.McRCIM.McGill.EDU>
Sender: news@src.dec.com (News)
Reply-To: msm@src.dec.com (Mark S. Manasse)
Organization: DEC Systems Research Center
Lines: 11

In one system I know of (namely, the only one that currently has patent
rights to use backing store), backing store guarantees are absolute: you
won't lose any of your old bits.

In return, attempts to configure windows and create windows fail when the
window system runs out of memory in which to maintain backing store.  One
can argue about whether this simplifies or complicates clients; I know
that I found it confusing as a user that I sometimes couldn't move a window 
from one place on the screen to another.

Mark