JavaScript/jQuery Gantt - toolbar

$(function () {
    $("#gantt").dxGantt({
        //...
        toolbar: {
            items: [
                'undo',
                'redo',
                'separator',
                {
                    widget: "dxButton",
                    options: {
                        text: "About",
                        icon: "info",
                        stylingMode: "text",
                        onClick: function () {
                            popupInstance.show();
                        }
                    }
                }
            ]
        }
    });
});