Firefox 21.0 You're connected on libervia, try to leave the page by entering any URL in the address bar and enter, using the navigation history, opening a bookmark --> you're still on libervia! If you're on libervia but not connected (login screen), the behavior is as expected: you can leave the page. I'm not sure if this should be considered as a bug or a functionality... it's after all not a bad idea to force the user properly close the session before leaving the page. But I'm not sure if he will understand it.