ExtJs 4中 panel怎么load一个新页...

     var mainPanel = Ext.create('Ext.Panel', {
            id:'main-panel',
            title: 'Anchor Layout',
            layout:'anchor',
            defaults: {bodyStyle: 'padding:15px'},
            items: [{
                title: 'Panel 2',
                height: 100,
                anchor: '-100',
                html: '<p>Width = container width - 100 pixels</p>'
            },{
                title: 'Panel 3',
                anchor: '-10, -262',
                html: '<p>Width = container width - 10 pixels</p><p>Height = container height - 262 pixels</p>'
            }]
//                    ,autoLoad:'http://www.baidu.com'
    });
怎么load新页呢
这个不好用 mainPanel.loader.load({url:"http://www.baidu.com",renderer:"component"})