Shoutbox

Click the options button(circled red in MeEtc's screenshot) and it'll produce a drop down, the very bottom option should be "Show the menu bar". Chec/Uncheck this and it should solve your problem.

Note: Pressing the Alt button brings this menu bar back up for quick access to some of the controls, but it will disappear after you let Alt go, however sometimes it gets stuck on some applications.