BUG REPORT: I still have the problem with the latest version that, after a few seconds of play, some window pops up in the background and starts interfering with the GL context, such that there are texture glitches, and occasionally I see the network-password dialog. I think there is still something going on with mouse capture/GLES foreground-window context, because I think the X server is still getting events in the background, doing things, and blitting under the GLES context incorrectly.
Incidentally, I saw this behaviour in the early porting stages of Wakebreaker, where windows 'underneath' the full-screen GLES context were still active and blitting, but I haven't seen it since I patched up the GLES init code somewhat. Maybe there is something about that context being built that leaves X events active?