title: Combo Box pop up and select using keyboard shortcuts
body: <pre><code>   public static void comboBoxActionPerform(JComboBox  comboBox)
      {
          String ACTION_KEY = "myAction";
  
          Action actionListener = new AbstractAction()
          {   
              @Override
              public void actionPerformed(ActionEvent actionEvent)
              {
                  JComboBox source = (JComboBox) actionEvent.getSource();
                  source.showPopup();
                  source.setFocusable(true);
              }
          };
  
          KeyStroke ctrlT = KeyStroke.getKeyStroke(KeyEvent.VK_L, InputEvent.CTRL_MASK);
          InputMap inputMap = comboBox.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
          inputMap.put(ctrlT, ACTION_KEY);
          ActionMap actionMap = comboBox.getActionMap();
          actionMap.put(ACTION_KEY, actionListener);
          locationTypeComboBox.setActionMap(actionMap);
      }
  </code></pre>
  
  <p>I have a com box and I call the above method to pop up combo box on keys (Ctrl+L) pressed.
  It pops up the combo box. But I can't select the items in it using UP/DOWN keys.
  Combo box get not focused when I pressed Ctrl+L. That might be the issue to be fixed.
  If I select the combo box manually and then up/down works fine. Need your help.</p>