protected IHierarchicalNodeLayout getRootLayout(
     IHierarchicalNodeModel model, final IHierarchicalEdgeModel tubeModel) {
   IHierarchicalEdgeLayout tubeLayout = getHierarchicalEdgeLayout(model);
   IHierarchicalNodeLayout layout = getHierarchicalNodeLayout(model);
   layout.setTubeModel(tubeModel);
   layout.setTubeLayout(tubeLayout);
   return layout;
 }