add(dropBalls(balls, 1, 2)).then().
add(dropBalls(balls, 3, 3));
// test barrier delay
CanvasImage sqimg = graphics().createImage(50, 50);
sqimg.canvas().setFillColor(0xFF99CCFF).fillRect(0, 0, 50, 50);
final ImageLayer square = graphics().createImageLayer(sqimg);
square.setOrigin(25, 25);
layer.addAt(square, 50, 300);
square.addListener(new Pointer.Adapter() {
@Override public void onPointerStart (Pointer.Event event) {