According to various observations in this bug report (especially #15 and #16), I believe this is not an X server bug but a bug in Metacity.
** Package changed: xorg-server (Ubuntu) => metacity (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to metacity in Ubuntu. https://bugs.launchpad.net/bugs/778083 Title: Switching workspaces does not always redraw everything necessary To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/metacity/+bug/778083/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
