extjs - ExtJs 4 手风琴布局显式展开和折叠

Question

Ext.create('Ext.panel.Panel', {
title: 'Accordion Layout',
width: 300,
height: 300,
    listeners:{

    render:function(comp){
        comp.items.items[0].collapse();
        comp.items.items[2].collapse();

        comp.items.items[1].expand();

    }},

defaults: {
    // applied to each contained panel
    bodyStyle: 'padding:15px'
},
layout: {
    // layout-specific configs go here
    type: 'accordion',
    titleCollapse: false,
    animate: true,
    activeOnTop: true
},
items: [{
    title: 'Panel 1',
    html: 'Panel content!'
},{
    title: 'Panel 2',
    html: 'Panel content!'
},{
    title: 'Panel 3',
    html: 'Panel content!'
}],
renderTo: Ext.getBody()
});

它不会改变第二个项目的图标。第一次不可扩展它的行为不符合预期。