Point fpt = (Point) offset_map.get(floater);
Point fpt = (Point) persistentBFC.offset_map.get(floater);
    private int getDownDistance(Box box, List list) {        for (int i = 0; i < list.size(); i++) {            Box floater = (Box) list.get(i);            Point fpt = (Point) offset_map.get(floater);            if (floater.y + floater.height - fpt.y > box.y) {                return floater.y + floater.height - fpt.y;            }        }        return 0;    }