Is there a way to attach an OnClick event to a tab switch in EXTJS?

I make the grid like this:

> 
> 
> ```
> var simple = new Ext.FormPanel({
>     labelWidth: '100%',
>     border:false,
>     width: '100%',
>             style: 
>             {
>                 height: '291px'
>             },
>     items: {
>         xtype: 'tabpanel',
>         activeTab: 0,
>         //labelWidth: 75, // label settings here cascade unless overridden
>         items:[{
>         url:'save-form.php',
>         title: 'Tab 1',
>   ...
> 
> ```
> 
> 

Thanks!