https://bugs.freedesktop.org/show_bug.cgi?id=110214
--- Comment #83 from Michel Dänzer michel@daenzer.net --- (In reply to Diego Viola from comment #82)
I found that I can't reproduce this bug with Xephyr -glamor_gles2 (git) but it still happens with -glamor.
Presumably the GL_NV_texture_barrier extension isn't available with GLES2, so this is the same as disabling that extension with OpenGL.