Comment 2 for bug 69406

I can affirm this bug, for my machines (about 4) this always happens (from breezy to gutsy).

Ihave attached my screenshot.
If anybody want's to reproduce this, just open a big (or if you have slower machine enough if you open a little) pdf, and scroll that fast. The pages that isn't being rendered yet have a big X instead of the page's contents, that X's lines gets out and makes that lines...