anchor.diff:  
     List<LineBarSpot>? _lastTouchedSpots;
   
  +  late bool _validForMouseTracker;
  +
     @override
     void performLayout() {
       size = computeDryLayout(constraints);
  
positive.code: }
  
  /// Renders our LineChart, also handles hitTest.
  class RenderLineChart extends RenderBox {
    RenderLineChart(LineChartData data, LineChartData targetData, double textScale,
        LineTouchCallback? touchCallback)
        : _data = data,
  
negative.code:   @override
    void handleEvent(PointerEvent event, covariant BoxHitTestEntry entry) {
      assert(debugHandleEvent(event, entry));
      _handleEvent(event);
    }
  
    @override
    PointerExitEventListener? get onExit => (PointerExitEvent event) {
          _handleEvent(event);
        };
  
    @override
    PointerEnterEventListener? get onEnter => null;
  
    @override
    MouseCursor get cursor => MouseCursor.defer;
  
    @override
    bool get validForMouseTracker => _validForMouseTracker;
  
    void _handleEvent(PointerEvent event) {
      if (_touchCallback == null) {
        return;
      }
  