/// <summary>
        /// The constructor is private: loading screens should
        /// be activated via the static Load method instead.
        /// </summary>
        private LoadingScreen(ScreenManager screenManager, bool loadingIsSlow,
                              GameScreen[] screensToLoad)
        {
            this.loadingIsSlow = loadingIsSlow;
            this.screensToLoad = screensToLoad;

            TransitionOnTime = TimeSpan.FromSeconds(0.5);
        }
        /// <summary>
        /// Activates the loading screen.
        /// </summary>
        public static void Load(ScreenManager screenManager, bool loadingIsSlow,
                                PlayerIndex? controllingPlayer,
                                params GameScreen[] screensToLoad)
        {
            // Tell all the current screens to transition off.
            foreach (GameScreen screen in screenManager.GetScreens())
                screen.ExitScreen();

            // Create and activate the loading screen.
            LoadingScreen loadingScreen = new LoadingScreen(screenManager,
                                                            loadingIsSlow,
                                                            screensToLoad);

            screenManager.AddScreen(loadingScreen, controllingPlayer);
        }