Oh noes, you broke it, Anarchist!! j/k xDDDD
F11 doesn't do anything that can make it into a real full screen of the game screen.
Maybe, there's a feature for us to do right-click on the server name, then choose "open link in a new window or new tab," we could get a bigger game screen.
Btw, pressing F11 won't make the Meebo bar disappear =o
I've just tested it on Chrome and Firefox.
If it disappears, it could be caused by the No Script that blocks it (for Firefox), or it's just simply a glitch.
Last time, I got Meebo glitch, too. Somehow, my Meebo bar was shown although I have disabled the "enable Meebo bar" feature.
So, just reset the Meebo bar ---> check/un-check the "enable Meebo bar" on the user setting under preference tab, and hopefully, it'll fix yours, too. ^^
Otherwise, check the No Script log (if you're using Firefox) to see if No Script accidentally blocked the Meebo :c