save-under support

[Patrick O'Donnell]

> Date: Fri, 23 Jan 2009 01:44:24 +0000
> From: =?UTF-8?Q?Rui_Tiago_Ca=C3=A7=C3=A3o_Matos?= <tiagomatos at gmail.com>
> 
> 2009/1/22 Patrick O'Donnell <pao at ascent.com>:
> > I've been told, recently, that "save-under and backing-store under
> > 8-bit [visuals] are no longer supported in recent X.org
> > releases". ...  could someone point me to where I would find more
> > authoritative information on the status of save-under and backing-store?
> 
> http://cgit.freedesktop.org/xorg/xserver/commit/?id=ae7f71a8b3d6756161e55d998d6eec37d2695c98
> 
> I'm afraid that's as official as it gets.

So, I take it that backing store (and from a commit last August, save
under) is being flushed, not just for 8-bit visuals, but completely.
The theory seems to be that "compositing" will do (almost) the same
thing.  (It's a shame that backing store = "Always" is being tossed to
the wind.  Apparently, backward compatibilty is given short shrift in
favor of "prettiness".)

Now, I have two additional troubles.  The problem we're seeing with
our application -- our main "chart" window (with backing store) is
being left blank under where a pop-up (with save-under) had been
mapped -- occurs in X.Org servers that predate the commit you pointed
me to.  So, the removal of backing store, and the much later removal
of save under don't seem to be the proximal problem.

Second, although, in my searching, I have found mention of "Composite"
and "compositing managers", I've yet to find a sufficiently detailed
explanation of what compositing is doing and how it is invoked or
configured for me to understand how I should be managing our
application's windows to make use of it.  Another pointer to a good
reference would be appreciated.

		- Pat