The bug report had expired, hence I reopened it. Yes, the issue is indeed still present in 12.04: occasionally unity simply "forgets" about a particular window and it does neither show up in the alt-tab not the alt-' and are also not listed in the launcher. I found no way of getting the window back, not even by killing compiz. I'll provide more symptoms if it occurs again.
** Changed in: unity (Ubuntu) Status: Invalid => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/927457 Title: Unity hides or loses subsequent windows/instances in launcher. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/927457/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs