private boolean prevExtendedButton(Object selected) {
    Integer currentIndex = myList.getSelectedButtonIndex();
    if (currentIndex == null) return false;

    if (--currentIndex < 0) currentIndex = null;
    boolean changed = myList.setSelectedButtonIndex(currentIndex);
    if (changed) {
      getContent().repaint();
    }
    return true;
  }
private boolean prevExtendedButton(Object selected)