Horizontal scroll bar on the tab bar toolbar

I have a TabPanel to which I add dynamic tabs. As the number of tabs increases, they become very small. Do we have a scrollbar on the tab toolbar? This code for my tab:

 var centerPanel = new Ext.TabPanel({
                        region: 'center',
                        deferredRender: false,
                        activeTab: 0,
                        autoScroll: true,
                        items: [
                        <if startUrl != "">
                            {
                                title: "${startName}",
                                html: "<iframe src='${startUrl}'  width='100%' height='100%' id='frame_${startName}' frameborder=0 name='name'/>"
                            }
                        </if>
                        ]

});