public function getSQLCompareDate($is_advanced, $op, $from, $to, $column)
 {
     return parent::getSQLCompareDate($is_advanced, $op, $from, $to, $column);
 }
 protected function getDatePicker($value, array $errors)
 {
     return $GLOBALS['HTML']->getBootstrapDatePicker("tracker_admin_field_" . $this->field->getId(), 'artifact[' . $this->field->getId() . ']', $value, array(), $errors, false);
 }