anchor.diff:      }
   
       // TODO: hold onto the subscription. Support dispose?
  -    _noteSync.changes.listen(_onNoteSyncChanged);
  +    filterPropertyChangeRecords(_noteSync, const Symbol('isUpdated'))
  +      .listen(_onNoteSyncIsUpdated);
   
       _updateNotesList();
     }
  
positive.code: 
    Map<String, Note> get _noteStorage => _noteSync.map;
  
    void _onNoteSyncChanged(List<ChangeRecord> records) {
      var forwardProps = records
          .where((ChangeRecord cr) => cr is PropertyChangeRecord)
          .map((pcr) => pcr.field)
          .where((Symbol field) => _NOTE_SYNC_FORWARD_PROPS.contains(field))
          .toList();
  
      for(var matchField in forwardProps) {
        _notifyChange(matchField);
      }
    }
  
    void _updateNotesList() {
  
negative.code:   void _notifyChange(Symbol prop) {
      notifyChange(new PropertyChangeRecord(prop));
    }
  }
  