There is nothing we can do here without further information. I will close this report now. Feel free to reopen with more info as requested if you still see this problem.
BTW, the full-screen button is F11 not F12 ** Changed in: firefox (Ubuntu) Status: Incomplete => Invalid -- can't undo fullscreen command (F12) https://bugs.launchpad.net/bugs/137186 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