/**
  * Add marker to map
  * @param string $value
  * @return boolean
  */
 public function addElementMarker($value)
 {
     $return = true;
     $stringsmarker = explode($GLOBALS['egMultiMaps_SeparatorItems'], $value);
     foreach ($stringsmarker as $markervalue) {
         if (trim($markervalue) == '') {
             continue;
         }
         $marker = new Marker();
         if (!$marker->parse($markervalue, $this->classname)) {
             $return = false;
             $this->errormessages = array_merge($this->errormessages, $marker->getErrorMessages());
         }
         if (!$marker->isValid()) {
             continue;
         }
         $this->markers[] = $marker;
         $this->elementsBounds->extend($marker->pos);
     }
     return $return;
 }