Try pressing the F11 key, or if you don't have that key, move your mouse to the top of the screen and select View>Full Screen. It is likely that you accidentally pressed F11 previously.
I'm marking this as "invalid" because it doesn't appear that Firefox is at fault. Please comment if the above fix doesn't work for you. ** Changed in: firefox-3.0 (Ubuntu) Status: New => Invalid -- Firefox goes to full screen without any means of reducing size or closing https://bugs.launchpad.net/bugs/583113 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