glClearColor(0.1f, 0.1f, 0.1f, 1.0f);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);

    glFrustum(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
    short w = GetSize().GetWidth(); // Get size of canvas.
    short h = GetSize().GetHeight();
    glViewport(0, 0, (GLint)w, (GLint)h);
    std::cout<<w<<h<<"\n";

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    //glTranslatef(0.0,0.0,-1.0);

    glColor3f(0.0f,0.0f,0.0f);  // Black.
    GraphicManager::DrawRectangle(-0.1f,0.1f,-0.1f,0.1f,0.0f);
    glColor3f(0.0f,0.0f,1.0f);  // Blue.
    GraphicManager::DrawRectangle(-0.1f,0.1f,-0.1f,0.1f,0.9f);

    Refresh();