message: Recreate MaterialRegistry after clearing the scene
diff: @@ -1034,6 +1034,10 @@ void MainWindow::buildMainMenuFile()
  frame->cancelFrame();
  frame->waitOnFrame();
  frame->remove("world");
  + // Recreate MaterialRegistry, clearing old registry and all materials
  + baseMaterialRegistry = sg::createNodeAs<sg::MaterialRegistry>(
  + "baseMaterialRegistry", "materialRegistry");
  +
  scene = "empty";
  refreshScene(true);
  }
  