Not sure I know who to assign this to, but I'm starting with the compositor. (you will need to install the resources it uses in res/leaky if you are not and linux and have leaky enabled; see the Makefile.in in tools/mozilla/leaky for what resources you will need) The glitch is this: if you use the viewer to look at the test case and open up several of the elements in the tree until you get a scroll bar, then scroll the window slightly, then click to close things back up so that you no longer need a scrollbar THEN you will end up with an invalid display...Anything that triggers a repaint fixes it...
Reassigning all compositor bugs to kevin.
The demonstration GIF dated 03/24/00 06:35 shows how the scrolling redraw bug interacts with the AllAdvantage viewbar under NT4 SP4, implying the problem might be connected with different physical/logical screen heights confusing the off-screen buffering algorithm (?) - Peet
*** This bug has been marked as a duplicate of 41386 ***