EXT控件挂事件的问题

扩展一个
var myTabPanel = Ext.extend(Ext.TabPanel,{  initEvents : function(){
        Ext.TabPanel.superclass.initEvents.call(this);
        this.on('add', this.onAdd, this);
        this.on('remove', this.onRemove, this);
        this.strip.on('mousedown', this.onStripMouseDown, this);
this.strip.on('mouseover',this.onStripMouseOver,this);
        this.strip.on('contextmenu', this.onStripContextMenu, this);
        if(this.enableTabScroll){
            this.strip.on('mousewheel', this.onWheel, this);
        }
    }

,onStripMouseOver : function(e){
e.preventDefault();
        var t = this.findTargets(e);
        if(t.item && t.item != this.activeTab){
            this.setActiveTab(t.item);
        }

}})Ext.onReady(function(){    var tabs = new myTabPanel({//......})});