@Override
  public void add(@NotNull Balloon newBalloon, @Nullable Object layoutData) {
    if (layoutData instanceof BalloonLayoutData
        && ((BalloonLayoutData)layoutData).welcomeScreen
        && newBalloon instanceof BalloonImpl) {
      addToPopup((BalloonImpl)newBalloon, (BalloonLayoutData)layoutData);
    }
    else {
      super.add(newBalloon, layoutData);
    }
  }
@Override
  public void add(@NotNull Balloon newBalloon, @Nullable Object layoutData)