public void move(MapView mv, Coord sc, Coord mc) {
            if (dragging) {
                Coord off = sc.add(o.inv());
                if ((mo == null) && (off.dist(Coord.z) > 5))
                    mo = mv.mc;
                if (mo != null) {
                    mv.mc = mo.add(s2m(off).inv());
                    moved(mv);
                }
            }
        }