I found out the reason, but I don't know how to reproduce the bug. Sometimes, metacity failed to recognize depth layer of "nautilus/nemo- background" and normal window, see the following ->
When I get trapped into this bug described above, running "killalll nautilus" under tty1 (Ctrl+F1), then all window except nautilus background can be seen !!!!!!!!!!!!!!!!!!! It seems that metacity thinks nautilus background has higher layer than normal windows. I don't think it's the bug from nautilus, because of the following proof: 1) even replacing nautilus with other similar file explorer like nemo, this bug also happens; 2) when using compiz or older version of metacity, this bug don't happen; So I think there should be some check of source code that is related with the top-level window covering other window. Don't let nautilus background (nemo -n) cover all normal windows. -- 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/1538111 Title: untraceable serious bug in metacity 3.18 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/metacity/+bug/1538111/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
