Ext4.1 Tab组件双击页签关闭

请问Ext4.1 Tab组件，如何实现双击页签关闭功能？

[code="java"]
var tabs = Ext.createWidget('tabpanel', {
renderTo: 'tabs1',
width: 450,
activeTab: 0,
defaults :{
bodyPadding: 10
},

    listeners:{
            afterrender:function(tab){
                var tabBar = tab.down("tabbar");
                 tab.mon(tabBar.el, {
                    scope: this,
                    dblclick:function(){
                        tabs.remove(tab.getActiveTab());
                    },
                    delegate: 'div.x-tab'
                });

            }
    },

[/code] 关键是这几行代码：
var tabBar = tab.down("tabbar");
tab.mon(tabBar.el, {
scope: this,
dblclick:function(){
tabs.remove(tab.getActiveTab());
},
delegate: 'div.x-tab'
});

[code="javaScript"]
var tabs = new Ext.TabPanel({
renderTo: 'tabs1',
width:450,
activeTab: 0,
frame:true,
defaults:{autoHeight: true},
items:[
{contentEl:'script', title: 'Short Text'},
{contentEl:'markup', title: 'Long Text'}
],
initEvents : function(){
Ext.TabPanel.superclass.initEvents.call(this);
this.on('add', this.onAdd, this, {target: this});
this.on('remove', this.onRemove, this, {target: this});
this.mon(this.strip, 'mousedown', this.onStripMouseDown, this);
this.mon(this.strip, 'contextmenu', this.onStripContextMenu, this);
if(this.enableTabScroll){
this.mon(this.strip, 'mousewheel', this.onWheel, this);
}
//monitor title dbclick
this.mon(this.strip,'dblclick',this.onTitleDbClick,this);
},
onTitleDbClick:function(e,target,o){
var t = this.findTargets(e);
if (t.item.fireEvent('beforeclose', t.item) !== false) {
t.item.fireEvent('close', t.item);
this.remove(t.item);

}
}
});
[/code]