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

              base.TransitionOnTime = TimeSpan.FromSeconds(0.5);
        }
        private void OnScreenRemoved(GameScreen screen)
        {
            // If we have a graphics device, tell the screen to unload content.
              if (HasDevice)
            screen.UnloadContent();

              screensToUpdate.Remove(screen);
        }
 private void OnScreenAdded(GameScreen screen)
 {
     // If we have a graphics device, tell the screen to load content.
       if (HasDevice)
     screen.LoadContent(Game.Content);
 }