Facebook chat question?

[Mary]

Why are there two parts on the facebook chat? I know the lower part has all the online friends. The upper half includes people whom I regularly talk to but there are like two or three who are there even if we rarely talk to each other. Sometimes even when they're offline, their names are still on the upper part of the list but there are others who only appear when they go online. What does that mean? We don't even talk to each other.

[Mohammed]

Its just that there was empty space and facebook filled it out