The same is happening here and with some other people (see bug #740905) when using the classical desktop. Almost sure it's a compiz' issue, not an unity's one.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/723014 Title: New window tracking system breaks in the case where windows try to restack relative to destroyed windows that were never mapped -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs