installComboBoxModelListeners(comboBox.getModel());
  protected void installComboBoxListeners()  {    // mouse listener that listens to mouse event in combo box    mouseListener = createMouseListener();    comboBox.addMouseListener(mouseListener);    // mouse listener that listens to mouse dragging events in the combo box    mouseMotionListener = createMouseMotionListener();    comboBox.addMouseMotionListener(mouseMotionListener);    // item listener listenening to selection events in the combo box    itemListener = createItemListener();    comboBox.addItemListener(itemListener);    propertyChangeListener = createPropertyChangeListener();    comboBox.addPropertyChangeListener(propertyChangeListener);  }