public void ShowSelectQuizWindow()
 {
     List<Domain.Quiz> templistQuizzes = Context.Quizzen.ToList();
     Quizzes = new ObservableCollection<QuizVM>(templistQuizzes.Select(quiz => new QuizVM(quiz)));
     selectQuizWindow = new SelectQuizWindow();
     selectQuizWindow.Show();
 }
        public void ShowPlay()
        {
            i = 0;
            selectQuizWindow = new SelectQuizWindow();

            selectQuizWindow.Show();
        }