Comment 17 for bug 327863

If it helps I'm seeing this bug when VNCing into a ubuntu box (I assume that the vnc server must be using xvfb). The vnc session has all the trimmings of a regular ubuntu desktop, GNOME, GDM etc, and looks the same as on a real monitor in every way (including the greeting screen where you log in).

I'm also seeing another scrollbar bug that only happens under VNC that may or may not be related. When scrolling a scrollbar with the mouse (either dragging the slider or clicking and holding on the scroll buttons) the slider will disappear when it hits the end of the scroll bar, and then reappear when you release the mouse. It is only a regression in mozilla-central and it occurs in the 2009-03-21 nightly, but not in the 2009-03-20 nightly. It may have the same root cause as this bug. One thing I would like to try when I can get around to it is to apply the patch in bug 485030 to a source tree from before/after 2009-03-21 (but before 485030 got checked in), and see if it still causes the same issue.