nt = myDiagram.transformViewToDoc(new go.Point(mx, my));
          // // if there's nothing at that point
          // if (myDiagram.findPartAt(point) === null) {
          //   // a return here doesn't allow the drop to happen
          //   return;
          // }
          // otherwise create a new node at the drop point
          myDiagram.startTransaction('new node');
          const newdata = {
            // assuming the locationSpot is Spot.Center:
            location: myDiagram.transformViewToDoc(
