java - Add Hide button to JComboBox

Question

I am trying to implement a custom JCombobox where I am trying to have checkboxes (JCheckBox) inside the dropdown and a simple "Hide" button at the bottom which should hide the drop-down menu. Right now my JCombobox has the checkboxes but i dont know how to proceed and add a hide button which would hide the menu. I would also want to stop the JCombobox from disappearing when an item (checkbox) is clicked upon.

The reason i want to a hide button is that selecting/de-selecting checkboxes makes some changes in my GUI like add/remove movies from a list in GUI. I want it to be more realtime so that changes made are more visible.

Below is my code. How do i do proceed ?

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class PopupMenuExample implements ActionListener
{
public JComboBox search_genre;
public static void main(String[] args)
{
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.getContentPane().add(new PopupMenuExample().getContent());
    f.setSize(300,160);
    f.setLocation(200,200);
    f.setVisible(true);
}

private JPanel getContent()
{
    String[] item_names = { "All Genre", "Horror", "Drama", "Comedy" };
    Boolean[] values ={ Boolean.TRUE, Boolean.TRUE, Boolean.TRUE, Boolean.TRUE };

    // instantiate items
    MenuItem[] items = new MenuItem[item_names.length];
    for(int j = 0; j < item_names.length; j++) items[j] = new MenuItem(item_names[j], values[j]);

    search_genre = new JComboBox(items);
    search_genre.setRenderer(new Renderer());
    search_genre.addActionListener(this);
    JPanel panel = new JPanel();
    panel.add(search_genre);
    return panel;
}

public void actionPerformed(ActionEvent e)
{
    if(e.getSource()==search_genre)
    {
        JComboBox cb = (JComboBox)e.getSource();
        MenuItem menu_item = (MenuItem)cb.getSelectedItem();
        System.out.println(menu_item.id);
        Renderer ccr = (Renderer)cb.getRenderer();
        ccr.checkBox.setSelected((menu_item.state = !menu_item.state));

        search_genre.setSelectedIndex(0);
    }   
}

}

Renderer class

class Renderer implements ListCellRenderer
{
    JCheckBox checkBox;

    public Renderer()
    {
        checkBox = new JCheckBox();
    }
    public Component getListCellRendererComponent(JList list,
                                                  Object value,
                                                  int index,
                                                  boolean isSelected,
                                                  boolean cellHasFocus)
    {
        MenuItem store = (MenuItem)value;
        checkBox.setText(store.id);
        checkBox.setSelected(((Boolean)store.state).booleanValue());
        checkBox.setBackground(isSelected ? Color.blue : Color.white);
        checkBox.setForeground(isSelected ? Color.white : Color.black);
        return checkBox;
    }
}

Menu item class

class MenuItem
{
    String id;
    Boolean state;

    public MenuItem(String id, Boolean state)
    {
        this.id = id;
        this.state = state;
    }
}