ext 鼠标悬浮事件 mouseover

求大神帮忙看看下面代码，应该怎么修改
mouseover : function(e) {
var index = grid
.getView()
.findRowIndex(e.getTarget());
return grid.getView().getRow(index).style.backgroundColor = 'row-bg-critical';
}
（这是写在grid的listeners的，后面是自己写的样式，求大神帮忙，刚接触ext，菜鸟一枚）

gridpanel么有mouseover事件吧。。数据行是itemmouseenter：http://docs.sencha.com/extjs/4.1.3/#!/api/Ext.grid.Panel-event-itemmouseenter

 itemmouseenter( this, record, item, index, e, eOpts )
Fires when the mouse enters an item.

Available since: 4.0.0

Parameters
this : Ext.view.View
record : Ext.data.Model
The record that belongs to the item
item : HTMLElement
The item's element
index : Number
The item's index
e : Ext.EventObject
The raw event object
eOpts : Object
The options object passed to Ext.util.Observable.addListener.