How: Datepicker in tbar?

[insnet]

Hi i have a grid with day-based data.

How do i add a "Choose Day" button in the tbar that opens a Datepicker?

tbar: [{
            xtype: 'tbsplit',
               text: 'Options',
               //handler: optionsHandler, // handle a click on the button itself
               menu: new Ext.menu.Menu({
                items: [
                     {xtype: 'datefield',
                         value: new Date()}
                ]
               })
        } // dropdown is undefined ;-(]