In any case, I don't think this could be due to ubuntu patches because the behavior is the same with fedora 13 beta
The versions used by fedora seem a bit more recent :
kernel 2.6.33.1-24-fc13.i686
xorg-x11-drv-nouveau 1:0.0.16-2.20100218git2964702.fc13
libdrm 2.4.19-1.fc13
In any case, I don't think this could be due to ubuntu patches because the behavior is the same with fedora 13 beta
The versions used by fedora seem a bit more recent : 1-24-fc13. i686 drv-nouveau 1:0.0.16- 2.20100218git29 64702.fc13
kernel 2.6.33.
xorg-x11-
libdrm 2.4.19-1.fc13