protected function renderFilterCellContent()
 {
     if (is_string($this->filter)) {
         echo $this->filter;
     } else {
         if ($this->filter !== false && $this->grid->filter !== null && $this->name !== null && strpos($this->name, '.') === false) {
             if (is_array($this->filter)) {
                 echo CHtml::activeDropDownList($this->grid->filter, $this->name, $this->filter, array('id' => false, 'prompt' => ''));
             } else {
                 if ($this->filter === null) {
                     echo CHtml::activeTextField($this->grid->filter, $this->name, array('id' => false));
                 }
             }
         } else {
             parent::renderFilterCellContent();
         }
     }
 }