XPresentPixmap flip with nouveau shows garbage
Basically similar issue to xf86-video-amdgpu#10 (closed) fixed by @daenzer with xf86-video-amdgpu!52 (merged)
Using the xfwm4 window manager with '--vblank=xpresent' gives a completely garbled display (but a screenshot is fine) with nouveau.
Note: modesetting and glamor do not work well on that old laptop (Dell M1710 with NV49 GeForce GO) so I am pretty stuck with nouveau.