I find out a workaround! :) Move the lower gnome panel to second screen with ALT + click-and-hold. I have attached a screenshot.
** Attachment added: "screenshot.png" https://bugs.launchpad.net/ubuntu/+source/gnome-panel/+bug/375503/+attachment/1729094/+files/screenshot.png -- maximized windows have titles covered by gnome-panel in twin view mode https://bugs.launchpad.net/bugs/375503 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs