Can't exit fullscreen mode: after F11, "exit Full screen", maximize button, fullscreen comes back immediately (Linux CentOS6 / firefox 17.0.5, no active plugin)
I recently put firefox (17.0.5) in full screen for a while on my Linux Laptop running CentOS6 (up to date on 3/5/2013)
I never managed to exit this full screen mode, neither with the contextual menu in the tab bar (appeared when I went to the top of the screen), nor with F11. Even when I close and restart Firefox, or when I shut off and restart the laptop, I get back to this fullscreen mode each time I open firefox. Only the failsafe mode (run with the command firefox -safe-mode) is not in full screen, and that was for me the only way to disable all my addons (as recommanded by some similar threads on the support forum).
I have no access to any menu, but thanks to the about:plugins special address, I could control that my plugins are off, and e for with about:support I got an overview of my installation, that seem OK. There is also about:config to edit my preferences, but I don't find the one which could be responsible for this behavior.