Yii-CGridView禁止列排序

'columns' => array (
	array (
		'class' => 'CCheckBoxColumn',
		'selectableRows' => '2',
		'value' => '$data->id', 
		'id' => 'delete'
	),
	array( 
		'header' => '标题',
		'name'=>'title',
		'sortable'=>false,//我在这里
	),
	array (
		'class' => 'CButtonColumn'
	)
),