[PATCH xserver] composite: Inhibit window background paint with manual subwindow redirection

[Ville Syrjälä]

On Fri, Jul 22, 2011 at 02:49:54PM -0400, Owen Taylor wrote:
> On Thu, 2011-07-21 at 00:24 +0300, Ville Syrjälä wrote:
> > > I did actually have to see it live to figure out what was going on ...
> > > but once I saw it, and thought about it a bit, I was able to avoid
> > > digging out the debugger.
> > > 
> > > What's going on is that for a window with a non-None background, the
> > > copying between the parent pixmap and the composite pixmap that we do
> > > isn't sufficient - all that copying is doing is making sure that things
> > > _look_ right initially - it doesn't actually suppress expose event
> > > generation and the background painting that happens during expose event
> > > generation.
> > 
> > The pointless expose events were supposed to be eliminated by another
> > patch set [1]. At least my test app [2] manages to redirect/unredirect
> > non-None windows w/o generating unnecessary expose events.
> 
> Hmm, OK, I had those patches applied, but figured that the expose events
> were being generated by some other path than Map/Unmap. It turns out
> that they were being generated because my test Mutter code wasn't
> ordering things correctly.
> 
> With that fixed, I can't reproduce any flickering with Evince. It
> redirects and unredirects seamlessly when I pop up a menu. (This is with
> GTK+-3, but there shouldn't be any difference from GTK+-2 in this
> regard.)
> 
> So, I'm not sure what was happening in your testing but I'm pretty happy
> with how things are working for me!

I suppose it's possible compiz does things in the wrong order as well. I
never bothered to investigate the issue properly since compiz and GTK+
weren't my real target with these patches.

-- 
Ville Syrjälä
syrjala at sci.fi
http://www.sci.fi/~syrjala/