This was actually with the 4.7.0-RC1 package.

To reproduce this issue:
Run qtdemo
Qt Declarative Examples >Corkboards>Display

Grab the background(corkboard) and click and drag (flick) out of the view area.

On X11 the window manager will flick black, the example will show corrupted graphics, and then the X11 server will die.

This does not occur when using qmlviewer with the corkboards example.

I suspect this requires the use of opengl to reproduce.

Tested on Ubuntu 10.04 with Nvidia binary drivers (provided by Ubuntu).