Solution is here: http://superuser.com/questions/332782/middle-click-tab-opening-stopped-working-in-firefox/332794#332794
for me: I simply uninstalled GreaseMonkey -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/843680 Title: middlemouse.openNewWindow setting ignored To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/843680/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
