function __toString()
 {
     $json_config = JsonHelper::encode($this->config);
     $this->afterHTML = HtmlHelper::inlineJavascript('jQuery(function(){$("#' . $this->getId() . '").datepicker(' . $json_config . ')});');
     $this->setAttribute('class', 'form_input_text form_ycalendar');
     return parent::__toString();
 }