public void registerUpDownHint(JComponent component) {
    DumbAwareAction.create(e -> {
      if (e.getInputEvent() instanceof KeyEvent) {
        int code = ((KeyEvent)e.getInputEvent()).getKeyCode();
        scrollBy(code == KeyEvent.VK_DOWN ? 1 : code == KeyEvent.VK_UP ? -1 : 0);
      }
    }).registerCustomShortcutSet(new CustomShortcutSet(KeyEvent.VK_UP, KeyEvent.VK_DOWN), component);
  }
public void registerUpDownHint(JComponent component)