This list shows %list% rooms on the server (your current room is shown in the title bar above the text area). To go to a room just click on the room name. You can also go to a room, or create a new one if allowed, by entering the name into the input field above and pressing Enter.
To update the list just press the 
icon.
You can also switch to a list of %if% %list% %!=% all %then% all rooms using the List All %else% active rooms using the List Active %end% link.