Near the area where you enter messages for the chat room you may find some of the following icons:
Toggle full screen: the chat will be auto-hidden and the play area will span the entire screen.
Auto-hide chat: the chat will hide on the right-side of the screen, and hovering over the panel by moving your mouse all the way to the right will bring it back into view.
Invite players: invite players from your contact list or the game lobby. Useful if you have made your game private.
Show settings dialog: brings up the dialog for current game settings and also for general, chat and contact list settings.
Tip of the day: Play full screen, auto-hide chat, invite players