When switching out of Spiral Knights (either by using Facebook Connect or clicking a link to the wiki or forums), the application will exit fullscreen mode to switch to the web browser, leaving you to go back to options to re-enable fullscreen mode.
It would be nice if there was the ability to set a hot key for switching to fullscreen mode, or make full screen a borderless window that hides the menu bar.
iMac (Intel Core 2 Duo)
Mac OS X 10.6.6
Seconding the borderless window mode. It's not essential, but a very welcome addition for those who alt-tab and especially don't play on their monitor's native resolution