I am using ExtJS 4.1.1. I extended a class from Ext.TabPanel, and added a new method "removeAllTabs()". The belowing is my code:

```
MyTabPanel = Ext.extend(Ext.TabPanel, {
    extend: 'Ext.tab.Panel',
    removeAllTabs:function(){
        this.items.each(function(item){
            this.remove(item);
        });
    }
}); 
tabPanel = Ext.create('MyTabPanel', {
    activeTab: 0,
    autoDestroy: false,
    defaults :{
        autoScroll: true,
        bodyPadding: 10,
        closeAction: "hide",
    },
    items: []
});

```

I can add some tabs to it dynamiclly like this:

tabPanel.add(App.tab1);
tabPanel.add(App.tab2);

Then I call this methmod to remove all tabs at somewhere:

tabPanel.removeAllTabs();

No error is reported, but nothing could be removed.

Then I modified the method as this:

```
MyTabPanel = Ext.extend(Ext.TabPanel, {
    extend: 'Ext.tab.Panel',
    removeAllTabs:function(panel){
        panel.items.each(function(item){
            panel.remove(item);
        });
    }
}); 

```

Then I call this methmod at somewhere:

tabPanel.removeAllTabs(tabPanel);

It can works well.

Why doesn't "this" work? How can I use "this" to achieve this purpose?

Thanks!