/**
  * Check if there are changes between old and new value for this field
  *
  * @param Tracker_Artifact_ChangesetValue $previous_changesetvalue The data stored in the db
  * @param mixed                           $new_value               May be string or array
  *
  * @return bool true if there are differences
  */
 public function hasChanges($previous_changesetvalue, $new_value)
 {
     return $previous_changesetvalue->getText() != $new_value;
 }
 /**
  * Fetch the html code to display the field value in tooltip
  *
  * @param Tracker_Artifact $artifact
  * @param Tracker_Artifact_ChangesetValue_String $value The ChangesetValue_String
  * @return string The html code to display the field value in tooltip
  */
 protected function fetchTooltipValue(Tracker_Artifact $artifact, Tracker_Artifact_ChangesetValue $value = null)
 {
     $hp = Codendi_HTMLPurifier::instance();
     $html = '';
     if ($value) {
         $html .= $hp->purify($value->getText(), CODENDI_PURIFIER_CONVERT_HTML);
     }
     return $html;
 }