comboBox.addFocusListener(focusListener); listBox.addFocusListener(focusListener);
editor.addFocusListener(focusListener);
  protected void installListeners()  {    // install combo box's listeners    propertyChangeListener = createPropertyChangeListener();    comboBox.addPropertyChangeListener(propertyChangeListener);    focusListener = createFocusListener();    comboBox.addFocusListener(focusListener);    listBox.addFocusListener(focusListener);    itemListener = createItemListener();    comboBox.addItemListener(itemListener);    keyListener = createKeyListener();    comboBox.addKeyListener(keyListener);    mouseListener = createMouseListener();    arrowButton.addMouseListener(mouseListener);    // install listeners that listen to combo box model    listDataListener = createListDataListener();    comboBox.getModel().addListDataListener(listDataListener);  }