private Actor keyboardFocus, scrollFocus;
  private final SnapshotArray<TouchFocus> touchFocuses = new SnapshotArray(true, 4, TouchFocus.class);
  /** Creates a stage with a {@link ScalingViewport} set to {@link Scaling#fill}. The stage will use its own {@link Batch}. */
  public Stage () {
    this(new ScalingViewport(Scaling.stretch, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), new OrthographicCamera()),
      null);
  }