I just submitted a patch for libgnomecanvas in openSUSE 10.3. The patch gets rid of the ugly tearing there is while repainting. You could see this when GDM paints the greeter's background, or when Evolution scrolls its message list --- it should all be smooth like a concrete vault now.
However, I've seen the patch give incorrect repainting when the canvas uses antialiased mode. I cannot find any programs that use AA mode, though --- GDM and Evolution are what I tested, mainly, but those don't use AA mode.
If after getting this update to libgnomecanvas you start seeing incorrect repainting in apps, please tell me about it :)