Not sure how I should name the bug. If I run an embedded weston (git) with pixman backend under weston (git) running on drm, the window doesn't show properly: by using the keyboard, on moving the mouse, I can make appear or disappear the window of the embedded weston. Whereas if I run the embedded weston (git) with pixman backend under weston (1.3) running on drm, everything is perfect. So it looks like the bug has nothing to do with the wayland pixman backend, but rather the handling of shm buffers with weston git.
I can't reproduce this. What hardware are you using? Can you include a screenshot?
Maybe this was fixed by http://cgit.freedesktop.org/wayland/weston/commit/?id=81038fba866633c012f0475977498a77fe7f4329 perhaps?
Pekka is right, I can't reproduce the bug anymore with last weston.
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