Hello, Thanks for reporting this. As far as I know, this has been normal Firefox behaviour since forever. If you want to close a single window, use the x button. If you want to kill all Firefox windows, use FIle->Quit.
** Changed in: firefox (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/1066432 Title: [Lubuntu 12.10] Multiple instances of Firefox are closed if just one is closed Status in “firefox” package in Ubuntu: Invalid Bug description: With Lubuntu 12.10, starting two instances of Firefox in safe mode (firefox -safe-mode) brings up two Firefox windows. In one of them, if I go File > Quit then both windows close down. Not good. ProblemType: Bug DistroRelease: Ubuntu 12.10 Package: firefox 16.0.1+build1-0ubuntu1 ProcVersionSignature: Ubuntu 3.5.0-17.28-generic 3.5.5 Uname: Linux 3.5.0-17-generic x86_64 ApportVersion: 2.6.1-0ubuntu3 Architecture: amd64 BuildID: 20121010223843 Date: Sat Oct 13 22:09:26 2012 InstallationMedia: Lubuntu 12.10 "Quantal Quetzal" - Beta amd64 (20120926) Plugins: Shockwave Flash - /usr/lib/flashplugin-installer/libflashplayer.so Google Talk Plugin Video Accelerator - /opt/google/talkplugin/libnpgtpo3dautoplugin.so (google-talkplugin) Google Talk Plugin - /opt/google/talkplugin/libnpgoogletalk.so (google-talkplugin) Profiles: Profile0 (Default) - LastVersion=Safe Mode/Safe Mode (Out of date) SourcePackage: firefox UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1066432/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp