Bug 198964 enabled smooth scrolling by default, resulting in bug 626245. Bug 626245 fixed some issue that made the effect worse; however the original regression, due to bug 198964, remains. Video demonstration is available here: http://youtu.be/fDH62trzUp4 Observe, in the video, how the lower left-hand corner of the plugin object extends beyond the gray background frame when the page is "bounce-scrolled."
(In reply to IU from comment #0) > ...when the page is "bounce-scrolled." Or simply quickly scrolled up or down
Any ideas guys how to fixed it? Pasting some info from bug #626245 (In reply to Robert O'Callahan (:roc) (Mozilla Corporation) from comment #88) > Unfortunately it's not really possible to completely fix it for windowed > plugins. We simply can't make the update of the window and the movement of > plugin widgets perfectly visually atomic. > > We could probably make it a little better by having some kind of callback > from the layer manger when it's just about to copy its backbuffer to the > window, and move the plugins at that moment. We'd have to do something to > ensure the area exposed by the plugins was part of the area composited by > the layer manager. (In reply to Robert O'Callahan (:roc) (Mozilla Corporation) from comment #89) > This would require some code restructuring because on Windows we'd have to > issue BeginPaint during layer tree composition. We'd probably have to add a > BeginPaint method to nsIWidget (no-op for all platforms but Windows), then > call that method from the layer manager just before we start drawing to the > window. On Mac that wouldn't work since we can't modify the widget hierarchy > during the 'draw' callback, so we'd have to carry on moving the plugins in > viewWillDraw/WillPaintWindow on Mac.
This is a minor problem, we'll get to it eventually.