Ext Js 给window或panel加上热键

如题，代码如下:

var OverTimeForm = new Ext.form.FormPanel({
		bodyStyle: 'padding: 15px 0 0 10px;',
		defaultType: 'textfield',
		items:[{
			fieldLabel: '超时时间(小时/h)',
			name: 'overTime',
			xtype: 'numberfield'
		},{
			xtype: 'panel',
			border: false,
			html: '<div style="color:red">设置终端刷卡后的有效时间!</div>'
		}],
		buttons:[{
			text: '确定',
			scope: this,
			handler: this.setOverTime
		},{
			text: '取消',
			scope: this,
			handler: this.cancleOverTime
		}],
//热键添加
		keys:[{
			key : Ext.EventObject.ENTER,
			fn : this.setOverTime,
			scope : this
		}]

	});