Not correctly working example

#include <iostream>
#include <SDL.h>
#include <SDL_opengl.h>
#include <CEGUI/CEGUI.h>
#include <CEGUI/RendererModules/OpenGL/GLRenderer.h>
#include <CEGUI/XMLParserModules/Expat/XMLParser.h>
#include <CEGUI/ImageCodecModules/DevIL/ImageCodec.h>

int main(int, char**)
{
  /***************************************
   * Init SDL
   ***************************************/

  if (SDL_Init(SDL_INIT_EVERYTHING) != 0){
    std::cout << "SDL_Init Error: " << SDL_GetError() << std::endl;
    SDL_Quit();
    return 1;
  }

  SDL_Window* p_window = SDL_CreateWindow("Test window", 100, 100, 640, 480, SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL);
  if (!p_window) {
    std::cerr << "failed to set up window." << std::endl;
    SDL_Quit();
    return 2;
  }

  SDL_ShowCursor(0);
  SDL_GLContext context = SDL_GL_CreateContext(p_window);

  //SDL_Renderer* p_sdl_renderer = SDL_CreateRenderer(p_window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
  //if (!p_sdl_renderer) {
  //  SDL_DestroyWindow(p_window);
  //  SDL_Quit();
  //  std::cerr << "Faield to set up renderer." << std::endl;
  //  return 3;
  //}
  //
  //SDL_Surface* p_image = SDL_LoadBMP("../hello.bmp");
  //SDL_Texture* p_imgtexture = SDL_CreateTextureFromSurface(p_sdl_renderer, p_image);
  //SDL_FreeSurface(p_image);
  //p_image = NULL;

  /***************************************
   * Init CEGUI
   ***************************************/

  //CEGUI::OpenGLRenderer& renderer = CEGUI::OpenGLRenderer::bootstrapSystem();
  CEGUI::OpenGLRenderer& renderer = CEGUI::OpenGLRenderer::create();
  CEGUI::DefaultResourceProvider* p_provider = new CEGUI::DefaultResourceProvider();
  CEGUI::ExpatParser* p_xml_parser = new CEGUI::ExpatParser();
  CEGUI::DevILImageCodec* p_imgcodec = new CEGUI::DevILImageCodec();

  CEGUI::System::create(renderer, p_provider, p_xml_parser, p_imgcodec, NULL);

  p_provider->setResourceGroupDirectory("schemes", "/usr/share/cegui-0/schemes/");
  p_provider->setResourceGroupDirectory("imagesets", "/usr/share/cegui-0/imagesets/");
  p_provider->setResourceGroupDirectory("fonts", "/usr/share/cegui-0/fonts/");
  p_provider->setResourceGroupDirectory("layouts", "/usr/share/cegui-0/layouts/");
  p_provider->setResourceGroupDirectory("looknfeels", "/usr/share/cegui-0/looknfeel/");
  p_provider->setResourceGroupDirectory("lua_scripts", "/usr/share/cegui-0/lua_scripts/");

  /* Now tell each of CEGUI’s resource-consuming classes (the "*Manager" classes)
   * which group of the filesystem provider to ask for its stuff. */
  CEGUI::ImageManager::setImagesetDefaultResourceGroup("imagesets");
  CEGUI::Font::setDefaultResourceGroup("fonts");
  CEGUI::Scheme::setDefaultResourceGroup("schemes");
  CEGUI::WidgetLookManager::setDefaultResourceGroup("looknfeels");
  CEGUI::WindowManager::setDefaultResourceGroup("layouts");
  CEGUI::ScriptModule::setDefaultResourceGroup("lua_scripts");

  CEGUI::SchemeManager::getSingleton().createFromFile("TaharezLook.scheme");
  CEGUI::FontManager::getSingleton().createFromFile("DejaVuSans-12.font");
  CEGUI::System::getSingleton().getDefaultGUIContext().setDefaultFont("DejaVuSans-12");
  CEGUI::System::getSingleton().getDefaultGUIContext().getMouseCursor().setDefaultImage("TaharezLook/MouseArrow");

  // Tell CEGUI how large our Window is. Forget this and you’ll never see anything.
  CEGUI::System::getSingleton().notifyDisplaySizeChanged(CEGUI::Sizef(640, 480));

  CEGUI::WindowManager& wmgr = CEGUI::WindowManager::getSingleton();
  CEGUI::Window* p_cegui_rootwin = wmgr.createWindow("DefaultWindow", "root");
  CEGUI::System::getSingleton().getDefaultGUIContext().setRootWindow(p_cegui_rootwin);

  CEGUI::FrameWindow* p_testframe = static_cast<CEGUI::FrameWindow*>(wmgr.createWindow("TaharezLook/FrameWindow", "testWindow"));
  p_testframe->setPosition(CEGUI::UVector2(CEGUI::UDim(0.25, 0.0), CEGUI::UDim(0.25, 0.0f)));
  p_testframe->setSize(CEGUI::USize(CEGUI::UDim(0.5f, 0.0f), CEGUI::UDim(0.5f, 0.0f)));
  p_testframe->setText("Hello, World!");
  p_cegui_rootwin->addChild(p_testframe);


  glClearColor(0, 0, 0, 255);

  /***************************************
   * Main loop
   ***************************************/
  bool quit = false;
  SDL_Event evt;
  while (!quit) {
    // Grab all events from the queue
    while (SDL_PollEvent(&evt)) {
      if (evt.type == SDL_QUIT) {
  quit = true;
      }
      else {
  std::cout << "Unknown event received." << std::endl;
      }
    }

    glClear(GL_COLOR_BUFFER_BIT);
    CEGUI::System::getSingleton().renderAllGUIContexts();
    SDL_GL_SwapWindow(p_window);

    //SDL_RenderClear(p_sdl_renderer);
    //SDL_RenderCopy(p_sdl_renderer, p_imgtexture, NULL, NULL);
    //SDL_RenderPresent(p_sdl_renderer);
  }

  /***************************************
   * Cleanup
   ***************************************/

  delete p_imgcodec;
  delete p_xml_parser;
  delete p_provider;

  //SDL_DestroyTexture(p_imgtexture);
  //SDL_DestroyRenderer(p_sdl_renderer);
  SDL_DestroyWindow(p_window);
  SDL_Quit();
  return 0;
}