I find that Blender is quite happy with compositing enabled, even with high poly counts, etc.
I re-ran the Heaven demo keeping the res change in addition to Unredirectfullscreen=true and it did the same session borkage.
I then ran the demo again, this time with Unredirectfullscreen=false and the res change and it worked without borking.
So I ran the demo one more time with Unredirectfullscreen=true and without the res change and there wasn't any borkage. So there's an issue there somewhere when res change plus glx context unredirectage are mixed together.
Thanks for all your answers.
reported my issue on nvnews: http://www.nvnews.net/vbulletin/show...02#post2258602