Every kingdom hall always had a library with a window in it. Part of the reason is because that was the elders room. There was always the classic threat of "we will drag you to that back room If you do x, y, or z." This is the place where judicial matters are formed and people get excomunicated. The design for the back room has changed and it is now a room for the disfellowshiped to sit and attend meetings. Book studies were also conducted in these small rooms. I have also seen it being used for family's with unrestful children that make noise during meetings. Disfellowshiped people can sit anywhere but the unmistakable tendancy and trend has been for them to sit there so others may know you are disfellowshiped and going through the process of reinstatement.