Ext Accordion 不展开

使用Ext Accordion 布局时默认展开第一个元素，当不需要展开第一项时需要给items中的每项指定collapsed:true

代码如下：

var accordion = new Ext.Panel({
		renderTo : Ext.getBody(),
		title: 'Accordion Layout',
		layout:'accordion',
		width:200,
		defaults: {
			// applied to each contained panel
			bodyStyle: 'padding:15px'
		},
		layoutConfig: {
			// layout-specific configs go here
			titleCollapse: true,
			collapseFirst : false,
			animate: true,
			hideCollapseTool : false,
			activeOnTop: false
		},
		items: [{
			title: 'Panel 1',
			id : 'id1',
			collapsed:true, 
			html: '<p>Panel content!</p>'
		},{
			title: 'Panel 2',
			collapsed:true, 
			id : 'id2',
			html: '<p>Panel content!</p>'
		},{
			title: 'Panel 3',
			collapsed:true, 
			id : 'id3',
			html: '<p>Panel content!</p>'
		}]
	});