Edge._dummyFromNode = this.diagram.nodeTemplate.copy();
      VirtualizedTreeEdge._dummyToNode = this.diagram.nodeTemplate.copy();
      VirtualizedTreeEdge._dummyLink.fromNode = VirtualizedTreeEdge._dummyFromNode;
      VirtualizedTreeEdge._dummyLink.toNode = VirtualizedTreeEdge._dummyToNode;
      this.diagram.add(VirtualizedTreeEdge._dummyFromNode);
      this.diagram.add(VirtualizedTreeEdge._dummyToNode);
      this.diagram.add(VirtualizedTreeEdge._dummyLink);

      super.commitLayout();
      // can't