code: function(){
  			var rect, obj, i;
              for (i=0, l=changed_objs.length; i<l; i++){
              	obj = changed_objs[i];
              	rect = obj._mbr || obj;
              	if (obj.staleRect == null)
              			obj.staleRect = {}
          		obj.staleRect._x = rect._x;
  				obj.staleRect._y = rect._y;
  				obj.staleRect._w = rect._w;
  				obj.staleRect._h = rect._h;
  
  				obj._changed = false
              }
              changed_objs.length = 0;
              dirty_rects.length = 0
  
  		}
docs: cleans up current dirty state, stores stale state for future passes