How do you remove the JComboBox 'click and see dropdown' functionality?

I have a JComboBox which uses GlazedLists to add type-ahead functionality. I want the user to type in a string and see type-ahead (this is working thanks to Glazedlists). However, I don't want users to be able to click the down arrow of the combobox and inspect the dropdown list. I've made the down arrow invisible and made the combobox editable so that it resembles a JTextField. However, you are still able to hover the mouse over the area where the down arrow used to be and click it. This results in the dropdown appearing. What do I change or which methods do I override in order to remove the 'click and get dropdown' functionality.

ComboBox<String> box = new ComboBox<String>();
box.setEditable(true);
box.setUI(new BasicComboBoxUI(){ // make the down arrow invisible
    protected JButton createArrowButton() {
       return new JButton() {
           public int getWidth() {
               return 0;
           }
       };
    }
});

SwingUtilities.invokeLater(new Runnable(){
     public void run(){
         Object[] elements = new Object[] {"java", "perl", "python", "haskell", "erlang", "groovy"};
         AutoCompleteSupport.install(box, GlazedLists.eventListOf(elements));       
     }
});

Override JButton#addMouseListener:

JComboBox<String> box = new JComboBox<>();
box.setEditable(true);
box.setUI(new BasicComboBoxUI() { // make the down arrow invisible
    protected JButton createArrowButton() {
        return new JButton() {
            public int getWidth() {
                return 0;
            }

            @Override
            public synchronized void addMouseListener(MouseListener l) {
            }
        };
    }
});