function shake_xy(n) {
 if (self.moveBy) {
 for (i = 10; i> 0; i--) {
 for (j = n; j> 0; j--) {
 self.moveBy(0,i);
 self.moveBy(i,0);
 self.moveBy(0,-i);
 self.moveBy(-i,0);
 }
 }
 }
 }