How to add Listbox / Select dropdown for shortcodes in WP 3.9 beta2 using TinyMCE?

I need a list-box for shortcodes in visual editor. With WP 3.8 I got it working like :

            createControl : function(n, cm) {
            switch (n) {

    case 'example':
            var mlb = cm.createListBox('example', {
                title : 'Example Shortcode',
                onselect : function(v) {
                   tinyMCE.activeEditor.selection.setContent(v);
                 }
            });

            // Add some values to the list box
    mlb.add('Shortcode', '[shortcode]Some Content Here[/shortcode]');

    // Return the new listbox instance
            return mlb;
    }

But these are not showing up in WP 3.9beta2. How to get it working?

Thanks in Advance.