anchor.diff:        // its owner to trigger state changes.
         child: LayoutBuilder(
           builder: (BuildContext context, BoxConstraints constraints) {
  -          lastIndicatorExtent = constraints.maxHeight;
  +          latestIndicatorBoxExtent = constraints.maxHeight;
             refreshState = transitionNextState();
             if (widget.builder != null && refreshState != RefreshIndicatorMode.inactive) {
               return widget.builder(
                 context,
                 refreshState,
  -              lastIndicatorExtent,
  +              latestIndicatorBoxExtent,
                 widget.refreshTriggerPullDistance,
                 widget.refreshIndicatorExtent,
               );
  
positive.code: 
      switch (refreshState) {
        case RefreshIndicatorMode.inactive:
          if (lastIndicatorExtent <= 0) {
            return RefreshIndicatorMode.inactive;
          } else {
            nextState = RefreshIndicatorMode.drag;
  
negative.code:         continue drag;
        drag:
        case RefreshIndicatorMode.drag:
          if (latestIndicatorBoxExtent == 0) {
            return RefreshIndicatorMode.inactive;
          } else if (latestIndicatorBoxExtent < widget.refreshTriggerPullDistance) {
            return RefreshIndicatorMode.drag;
          } else {
            if (widget.onRefresh != null) {
  