protected void installEditorKeyListener(@NotNull ComboBoxEditor cbe) {
    Component ec = cbe.getEditorComponent();
    if (ec != null) {
      editorKeyListener = new KeyAdapter() {
        @Override
        public void keyPressed(KeyEvent e) {
          process(e);
        }

        @Override
        public void keyReleased(KeyEvent e) {
          process(e);
        }

        private void process(KeyEvent e) {
          final int code = e.getKeyCode();
          if ((code == KeyEvent.VK_UP || code == KeyEvent.VK_DOWN) && e.getModifiers() == 0) {
            comboBox.dispatchEvent(e);
          }
        }
      };

      ec.addKeyListener(editorKeyListener);
    }
  }
protected void installEditorKeyListener(@NotNull ComboBoxEditor cbe)