I have come across this bug quite frequently and sometimes it can be very annoying. When you're waiting for a game in lobby and is writing something in world chat, the chat message changes to local when you join a game. If you press enter the message will be output in local chat, so you have to cut+paste the chat into the world chat window to change chat back to world. Could you change it so if there's any text in the input box, the world chat will be the active window when joining a game?
