scrolling display bug in 21.5-b11

Hi, Run: xemacs -vanilla then evaluate the following in the *scratch* buffer: (defun scroll-up-1 (arg) (interactive "_p") (scroll-up (if arg arg 1))) (global-set-key 'kp-enter 'scroll-up-1) and now do: M-x w3 <RET> C-o www.xemacs.org <RET> ;; open xemacs.org website C-x 2 ;; split window C-x o ;; move to lower window Finally, hold and repeat the kp-enter key. As the lower window scrolls up, the top window's modeline and last couple lines are overwritten by the contents of the lower window which are being scrolled up. It doesn't fix itself when you stop scrolling, but does if you hit C-l to redraw the frame. I first encountered this bug reading an HTML attachment in Gnus, but the reproducer above uses w3 directly so I don't have to send my mail file. It is not necessary for there to be embedded images, just text of varying heights. This exists in 21.4.6 and 21.4.12 as well. thanks, Greg