anchor.diff:        }
       }
   
  -    this.previouslyOpened = openedPaths;
  +    this._previouslyOpened = openedPaths;
   
       _rootNodes.clear();
       this.children.clear();
  
positive.code:   // before the json was reloaded.  Storing this information
    // makes it possible to re-open the tree to where it
    // was before.
    Set<String> previouslyOpened = new Set<String>();
  
    TreeTable.created() : super.created() {}
  
  
negative.code:     couldBeOpened.addAll(_rootNodes);
      while (couldBeOpened.isNotEmpty) {
        LogicalRow next = couldBeOpened.removeFirst();
        if (_previouslyOpened.contains(next.id)) {
          next.click();
          couldBeOpened.addAll(next.children);
        }
  