anchor.diff:              node: child,
               child: Treemap.fromRoot(
                 rootNode: child,
  -              levelsVisible: levelsVisible - 1,
  -              onRootChangedCallback: onRootChangedCallback,
  +              levelsVisible: widget.levelsVisible - 1,
  +              onRootChangedCallback: widget.onRootChangedCallback,
                 width: newWidth,
                 height: newHeight,
               ),
  
positive.code:   /// Selecting this widget will trigger a re-root of the tree
    /// to the associated [TreemapNode].
    ///
    /// The default value for newRoot is [rootNode].
    Widget buildSelectable({@required Widget child, TreemapNode newRoot}) {
      newRoot ??= rootNode;
      return Tooltip(
        message: rootNode.displayText(),
        waitDuration: tooltipWait,
        preferBelow: false,
        child: InkWell(
          onTap: () {
            onRootChangedCallback(newRoot);
          },
          child: child,
        ),
  
negative.code:   Container buildCell() {
      return Container(
        decoration: BoxDecoration(
          color: widget.rootNode.displayColor,
          border: Border.all(color: Colors.black87),
        ),
        child: Center(
          child: widget.height > Treemap.minHeightToDisplayCellText
              ? buildNameAndSizeText(
                  textColor:
                      widget.rootNode.showDiff ? Colors.white : Colors.black,
                  oneLine: false,
                )
              : const SizedBox(),
  