private static boolean isEmpty(@Nullable Window window) {
    ProjectFrameHelper frameHelper = ProjectFrameHelper.getFrameHelper(window);
    if (frameHelper != null) {
      BalloonLayout layout = frameHelper.getBalloonLayout();
      if (layout instanceof BalloonLayoutImpl) {
        // do not show notification if others exist
        return ((BalloonLayoutImpl)layout).isEmpty();
      }
    }
    return false;
  }
private static boolean isEmpty(@Nullable Window window)