anchor.diff:  
     bool _canKeepMarkerInCenter = false;
     void _keepMarkerInCenter() {
  -    if (_canKeepMarkerInCenter && editionMode) {
  +    if (_canKeepMarkerInCenter && _editionMode) {
         if (_marker != null) {
           _marker.position = _googleMap.center;
           mapPosition.innerHtml = "${_googleMap.center.lat}, ${_googleMap.center.lng}";
  
positive.code: 
      mapPosition = new DivElement();
      mapAddress = new DivElement();
  
      map.append(mapAddress);
      map.append(mapCanvas);
      map.append(mapPosition);
  
      final mapOptions = new MapOptions()
        ..center = defaultPosition
        ..zoom = 6
        ..mapTypeId = MapTypeId.ROADMAP
        ..streetViewControl = false;
  
  
negative.code:     _googleMap.onCenterChanged.listen((_) {
        _keepMarkerInCenter();
      });
      
      lock.onClick.listen((_){
        editionMode = !lock.checked ;
      });
      
      _googleMap.onMouseover.listen((_) {
        _canKeepMarkerInCenter = true;
      });
  