This have been reported about a week ago, but seems to have come unnoticed. I found a very bright reproduction for this bug. I see it in 20.3 and in 21.0 beta 37 under X on Solaris, with lucid sb. xemacs -vanilla C-x 3 Now get a grip on any of the horizontal scrollbars, and move the hanle left and right *real* *real* *slowly*. When moving right, the handle makes its way about 1+1/3 of the distance made by the pointer. When you move left, the handle moves 3-4 times further than the pointer! Kirill