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From: ea08+@andrew.cmu.edu (Eric A. Anderson)
Newsgroups: comp.windows.x
Subject: Save Under Bit Implementation
Message-ID: <8bBX6we00Vpc89mW1i@andrew.cmu.edu>
Date: 6 Nov 90 03:45:00 GMT
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 32

I was wondering if this is being fixed.
When you set the save under bit on a window, the default MIT server
implements this as setting backing store on every window it occludes. 
This has a couple of problems.
First, lets say I'm running tvtwm, and I have a big virtual window.  I
bring up a menu and pop, My server grows to 10Meg.
A similar problem occurs on a monochrome machine although it is 1/8 of
the size.
I noted in the source that it says 'Never set backing store on root window.'
Could something be added with the Backing store variable as 'Never give
me a backing store?'  It seems somehow foolish to save the entire window
when in general menus only occlude a small portion of the screen, and
don't move.  I know for example that the Dec X server does do something
like that, becuase it does not grow like the MIT server does under
tvtwm. (Of course it could just not do save under, but I'd hope not.)
I'm not sure if this is something that is being looked into, but It
might be something that should be fixed.  Something to fix the server so
that it only save the occluded region would be possible, but I'm not
sure how it would be implemented.  On the other hand the 'Never give a
backing store' could work, and would allow windows which really
shouldn't get backing stores, like the tvtwm virtual root, to not get
backing stores.
I hope I haven't rambled too much.
Thanks.
          -Eric
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"My life is full of additional complications spinning around until
 it makes my head snap off."
           -Unc. Known.
"You are very smart, now shut up."
           -In "The Princess Bride"
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