Wt

i'm using these examples. [[[https://www.webtoolkit.eu/widgets/navigation/menu]]].

it's compiled well but not showing any this except title of the page.

my code is:

#include <Wt/WApplication.h>
#include <Wt/WBreak.h>
#include <Wt/WContainerWidget.h>
#include <Wt/WMenu.h>
#include <Wt/WStackedWidget.h>
#include <Wt/WTextArea.h>

//using namespace Wt

class WMenu:public Wt::WApplication{
   private:
        int abc=1;
   public:
        WMenu(const Wt::WEnvironment& env);   //constructor
};

WMenu::WMenu(const Wt::WEnvironment& env):Wt::WApplication(env)

{
   setTitle("this is test");
   auto container = Wt::cpp14::make_unique<Wt::WContainerWidget>();

   // Create a stack where the contents will be located.
   auto contents = Wt::cpp14::make_unique<Wt::WStackedWidget>();

   Wt::WMenu *menu = container->addNew<Wt::WMenu>(contents.get());
   menu->setStyleClass("nav nav-pills nav-stacked");
   menu->setWidth(150);
// Add menu items using the default lazy loading policy.
   menu->addItem("Internal paths", Wt::cpp14::make_unique<Wt::WTextArea>("Internal paths contents"));
   menu->addItem("Anchor", Wt::cpp14::make_unique<Wt::WTextArea>("Anchor contents"));
   menu->addItem("Stacked widget", Wt::cpp14::make_unique<Wt::WTextArea>("Stacked widget contents"));
   menu->addItem("Tab widget", Wt::cpp14::make_unique<Wt::WTextArea>("Tab widget contents"));
   menu->addItem("Menu", Wt::cpp14::make_unique<Wt::WTextArea>("Menu contents"));

   container->addWidget(std::move(contents));
}
int main(int argc, char **argv)
{
    return Wt::WRun(argc, argv, [](const Wt::WEnvironment& env) {
      return std::make_unique<WMenu>(env);
    });
}

Please let me know what's wrong with this code?