How to Listen for JCombobox Selection Event

When I select the JCombobox I want to handle an event when its selected and the dropdown is shown as well as handle the event when the drop down disappears and the JCombobox is de-selected.

Note, i'm not looking to listen for an item selection change but for when the user selects the JCombobox and the UI pops out the Dropdown.

You want to use addPopupMenuListener which uses the following interface:

public interface PopupMenuListener extends EventListener {

    /**
     *  This method is called before the popup menu becomes visible 
     */
    void popupMenuWillBecomeVisible(PopupMenuEvent e);

    /**
     * This method is called before the popup menu becomes invisible
     * Note that a JPopupMenu can become invisible any time 
     */
    void popupMenuWillBecomeInvisible(PopupMenuEvent e);

    /**
     * This method is called when the popup menu is canceled
     */
    void popupMenuCanceled(PopupMenuEvent e);
}