Created attachment 327806 [details]
photograph of corrupted text

When I scroll up and back down, the text that was just below the bottom of the screen before the movement is often shifted vertically by a few pixels.  Same thing at the top of the screen when I scroll up.  I've only seen it happen when I use the scroll wheel or the arrow keys, not when I yse the scrollbar.  It only happens when smooth scrolling is enabled.  It doesn't happen in firefox 3.0.5 downloaded directly from mozilla, only in the fedora build.

I can't seem to get a screenshot of it--when I take a screenshot the window redraws and the problem goes away.  I'm attaching a photo.