It seems that if you call eglMakeCurrent to switch between two surfaces then Mesa gets very confused and decides that there is no context any more so nothing paints. Attached is a patch to mesa-demos to modify the 'tri' demo for EGL/GLES2 so that it draws to two windows.

I've bisected the problem as much as I can to a range of commits but within that range instead of just not painting the demo segfaults. I'm guessing this is a separate problem. The bisect then looks like this:

547e7619aac74ae13bdaa7fdf403a4ceb5212467 <--- first known bad commit
d1acb920163ab0f39ff2fc72b85fc7bf16c37262 <--- unknown, segfaults
                  .
                  .                       }
                  .                       } all in this range seem to segfault
                  .                       }
                  .
d19afc57fe49816f3f3290410e0124d326577be2 <--- unknown, segfaults
dc4f845c37a8446de19036e24fd397a0aa864c02 <--- last known good commit

547e7619 seems like a good candidate to be the culprit because it makes changes in the right area.

The bug breaks Clutter because Clutter relies on being able to switch between surfaces even if there is only one stage. It needs to create an initial invisible dummy window before creating any stage so that it can bind the context to something in order to query the features.