 the viewport,
            // or if the link might cross over the viewport
            b.set(n.bounds);
            b.unionRect(parent.bounds);
            if (b.intersectsRect(viewb)) {
              model.addNodeData(n); // add N so that link to parent appears
              const child = diagram.findNodeForData(n);
              if (child !== null) {
                const link = child.findTreeParentLink();
                if (link !== null) {
                  // do this now to avoid delayed routing outsi