Comment # 83 on bug 110214 from Michel Dänzer

(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.