Comment 36 for bug 638808

Btw, make sure to restart X (e.g. `sudo service gdm restart` would do it). I found this resolved the white screen issue, but it is possible there are subsequent usage issues.

Mark, some further info I've gleaned. The root cause here actually is not a bug in X, but rather that clutter has been depending on a bug in mesa which was fixed in mesa 7.9. My bisection work actually just restored the buggy code that clutter depends on.

The proper fix is to fix Clutter... Specifically https://bugs.edge.launchpad.net/ubuntu/+source/clutter-1.0/+bug/632352 needs to be resolved.

As I understand the bug, Mesa 7.8 would spam event notifications to all clients regardless of whether they wanted them. Clutter used this to do its updates. In Mesa 7.9, it changed to only send notices to clients that registered interest in them. Since clutter doesn't register interest, it doesn't get updated, so you just see a white screen. The patch in bug #632352 enables clutter to request these updates. The "fix" I uploaded causes mesa to resume its old spammy behavior.