Description of problem: Followup from Bug 1417996 c17: https://github.com/stransky/gecko-dev > The problem was that Firefox committed surface state to a surface of a > subsurface which had been destroyed. Mutter did not handle that well, and > the patch in the upstream bug fixes that.
Should be fixed in latest github repo, see https://bugzilla.gnome.org/show_bug.cgi?id=784319 for reference and patch.