code: public UI wrapWindow(Window window) {
          final UI ui = wrapLayout(new VerticalLayout());
          ui.addWindow(window);
          return ui;
      }
docs: Wraps the specified {@link Window} into a UI. Adds the specified pop-up
  window to a simple, empty vertical layout.
  
  @param window the pop-up window to wrap
  @return an application displaying that pop-up window