save-under support

[Patrick O'Donnell]

>From: Adam Jackson <ajax at nwnk.net>
>Date: Wed, 04 Feb 2009 17:17:32 -0500
>
>On Thu, 2009-01-22 at 17:25 -0500, Patrick O'Donnell wrote:
>> I've been told, recently, that "save-under and backing-store under
>> 8-bit [visuals] are no longer supported in recent X.org
>> releases". ...
>
>As mentioned downthread, bs and saveunders have never been guarantees,
>and did have real bugs that would require the application to correctly
>respond to Expose events.

Our toolkit did have some mangling of Expose events, but it was
supposed to handle the case in question.  I found a bug a couple days
ago (no surprise, eh?), and our apps now redisplay properly, though
much more slowly.  (Thus, our "dependence" on bs.)

>As a trivial workaround, you can enable compositing for your own windows
>with XCompositeRedirectSubwindows(dpy, win, CompositeRedirectAutomatic).
>If a compositing manager is active, this will have no effect; otherwise,
>it will behave essentially the same as bs's WhenMapped state, except,
>you know.  Good.

Thanks.  I'll look into this.  Unfortunately for me, our toolkit and
apps must work with many different kinds of X servers of many
vintages, so I can't really depend on XCompositeRedirectSubwindows
being present.  (I'm still working on finding a good explication of
the compositing protocol and API...)

		- Pat