This command is for Java users only, it will allow the Java user to join additional rooms, without leaving any rooms they are in.
Example:
/newjoin #conferenceroom
The new rooms will show up on the bottom of the chat window as buttons that can be clicked on to switch between which room is being viewed. If something is said in a room that you are not watching, then the button will change color to inform you that you should look at that room.