anchor.diff:              // Vertical guideline that will connect [node] with its overlapping
               // children nodes. The line will end at [node]'s last child.
               final verticalGuidelineX = node.rect.left + 1;
  -            // Subtract [topOffset] so the coordinates of the guidelines are
  -            // based on a starting y of 0.
  -            final verticalGuidelineStartY = node.rect.bottom - topOffset;
  +            final verticalGuidelineStartY = node.rect.bottom;
               final verticalGuidelineEndY =
  -                chartNodesByEvent[event.children.last].rect.centerLeft.dy -
  -                    topOffset;
  +                chartNodesByEvent[event.children.last].rect.centerLeft.dy;
               verticalGuidelines.add(VerticalLineSegment(
                 Offset(verticalGuidelineX, verticalGuidelineStartY),
                 Offset(verticalGuidelineX, verticalGuidelineEndY),
  
positive.code:       if (line.intersects(visible)) {
          canvas
            ..beginPath()
            ..moveTo(line.start.dx, line.start.dy + topOffset)
            ..lineTo(line.end.dx, line.end.dy + topOffset)
            ..closePath()
            ..stroke();
        }
  
negative.code:               final childNode = chartNodesByEvent[child];
                final horizontalGuidelineStartX = verticalGuidelineX;
                final horizontalGuidelineEndX = childNode.rect.left;
                final horizontalGuidelineY = childNode.rect.centerLeft.dy;
                horizontalGuidelines.add(HorizontalLineSegment(
                  Offset(horizontalGuidelineStartX, horizontalGuidelineY),
                  Offset(horizontalGuidelineEndX, horizontalGuidelineY),
  