ExtJS How to add a custom panel to rowexpander

Question

Here's an EXTJS rowexpander implementation

http://jsfiddle.net/Litote0707/xPpf2/

When you expand it, you can see the price.

Instead of price, can I show another custom grid something like this?

Ext.define('my.app.main.CustomList', {
    extend: 'Ext.grid.Panel',
    title: 'List in Rowexpander',
    store: Ext.data.StoreManager.lookup('myStore'),
    columns: [
        { text: 'Name', dataIndex: 'name' },
        { text: 'Email', dataIndex: 'email', flex: 1 },
        { text: 'Phone', dataIndex: 'phone' }
    ],
    height: 200,
    width: 400
});