How to add a checkbox column in a gridpanel in ExtJS4.0.2

[bill_chuang]

Now I want to add a checkbox column in a gridpanel like this.未命名.jpg
Andbody help me?

[slemmon]

There is an example here on this page:
http://dev.sencha.com/deploy/ext-4.0.2a/examples/grid/grid-plugins.html

*extract

var sm = Ext.create('Ext.selection.CheckboxModel');    var grid2 = Ext.create('Ext.grid.Panel', {        store: getLocalStore(),        selModel: sm,        columns: [            {text: "Company", width: 200, dataIndex: 'company'},            {text: "Price", renderer: Ext.util.Format.usMoney, dataIndex: 'price'},            {text: "Change", dataIndex: 'change'},            {text: "% Change", dataIndex: 'pctChange'},            {text: "Last Updated", width: 135, renderer: Ext.util.Format.dateRenderer('m/d/Y'), dataIndex: 'lastChange'}        ],        columnLines: true,        width: 600,        height: 300,        frame: true,        title: 'Framed with Checkbox Selection and Horizontal Scrolling',        iconCls: 'icon-grid',        renderTo: Ext.getBody()    });

[bill_chuang]

There is an example here on this page:
http://dev.sencha.com/deploy/ext-4.0.2a/examples/grid/grid-plugins.html

*extract

var sm = Ext.create('Ext.selection.CheckboxModel');    var grid2 = Ext.create('Ext.grid.Panel', {        store: getLocalStore(),        selModel: sm,        columns: [            {text: "Company", width: 200, dataIndex: 'company'},            {text: "Price", renderer: Ext.util.Format.usMoney, dataIndex: 'price'},            {text: "Change", dataIndex: 'change'},            {text: "% Change", dataIndex: 'pctChange'},            {text: "Last Updated", width: 135, renderer: Ext.util.Format.dateRenderer('m/d/Y'), dataIndex: 'lastChange'}        ],        columnLines: true,        width: 600,        height: 300,        frame: true,        title: 'Framed with Checkbox Selection and Horizontal Scrolling',        iconCls: 'icon-grid',        renderTo: Ext.getBody()    });

Thanks.It's helpful