It is an error if the object obj currently belongs to a different layer. If the object already is not in this layer, this method does nothing. Just before changing the object's GoObject.Layer property to null, the object's document or view will be notified with a Changed hint of RemovedObject. During that notification the object's GoObject.BeingRemoved property will be true. For convenience, if the object belongs to a GoGroup, this method will remove the object from the group.