// look for a drop directly onto a Node or Link
      const it = myDiagram.findPartsAt(point).iterator;
      while (it.next()) {
        const part = it.value;
        if (part === newNode) continue;
        // the drop happened on some Part -- call its mouseDrop handler
        if (part && part.mouseDrop) {
          const e = new go.InputEvent();
          e.diagram = myDiagram;
          e.documentPoint = point;
          e.viewPoint = myDiagram.transformDocToView(point);
          e.up = true;
        