anchor.diff:    GMap _googleMap;
     Marker _marker;
     DivElement mapPosition;
  +  bool editionMode = true;
   
  -  MapGeoLocation(this.map, this.mapSize, this.markerUrl, this.markerSize) {
  +  MapGeoLocation(this.map, this.mapSize, this.markerUrl, this.markerSize, {this.editionMode}) {
       this.map.style
         ..position = "relative"
         ..visibility = null;
  
positive.code: 
      _googleMap = new GMap(mapCanvas, mapOptions);
      _googleMap.onCenterChanged.listen((_) {
        keepMarkerInCenter();
      });
      _googleMap.onMouseover.listen((_) {
        _canKeepMarkerInCenter = true;
  
negative.code:   }
  
    bool _canKeepMarkerInCenter = false;
    void _keepMarkerInCenter() {
      if (_canKeepMarkerInCenter && editionMode) {
        if (_marker != null) {
          _marker.position = _googleMap.center;
          mapPosition.innerHtml = "${_googleMap.center.lat}, ${_googleMap.center.lng}";
        }
      }
    }
  
  