Maybe this is a bug?
<?php $this->widget('zii.widgets.grid.CGridView', array(
'id'=>'lang-grid',
'dataProvider'=>$model->search(),
'filter'=>$model,
'columns'=>array(
'lang_id',
'lang_title',
array(
'name'=>'default',
'value'=>'$data->default',
'type'=>'boolean',
'filter'=>array(1=>'Yes', 2=>'No'),
),
array(
'class'=>'CButtonColumn',
),
),
)); ?>
Can not filter by the "default" Column, because the word "default" is a MySQL keyword.