public static object ShowPopUp(DifficultyLevel level)
        {
            PopUpWindow window = new  PopUpDifficulty(level);

            window.ShowDialog();

            return(window.Selected);
        }
        public static object ShowPopUp(DifficultyLevel level)
        {
            PopUpWindow window = new  PopUpDifficulty(level);
            window.ShowDialog();

            return window.Selected;
        }