pBack(link)) link.isHighlighted = true;
      },
      mouseDragLeave: (e, link) => {
        link.isHighlighted = false;
      },
      // if a node from the Palette is dropped on a link, the link is replaced by links to and from the new node
      mouseDrop: dropOntoLink
    })
      .add(
        new go.Shape({ isPanelMain: true, stroke: 'transparent', strokeWidth: 8 })
          .bindObject('stroke', 'isHighlighted', (h) => (h ? 'lime' : 'transparent')),
        new go.Shape({ isPanelMain: true, stroke: