public void onEvent(ThemeSelectedEvent evt)
        {
            mSelectedTheme = evt.theme;
            mScreenController.openScreen(ScreenController.Screen.DIFFICULTY);

            Bitmap bitmap          = GameUtility.ScaleDown(Resource.Drawable.background, GameUtility.ScreenWidth(), GameUtility.ScreenHeight());
            Bitmap backgroundImage = GameThemes.getBackgroundImage(mSelectedTheme);

            backgroundImage = GameUtility.Crop(backgroundImage, GameUtility.ScreenHeight(), GameUtility.ScreenWidth());
            Drawable[] backgrounds = new Drawable[2];
            backgrounds[0] = new BitmapDrawable(Application.Context.Resources, bitmap);
            backgrounds[1] = new BitmapDrawable(Application.Context.Resources, backgroundImage);

            TransitionDrawable crossfader = new TransitionDrawable(backgrounds);

            mBackgroundImage.SetImageDrawable(crossfader);
            crossfader.StartTransition(2000);
        }
 public virtual void onEvent(ThemeSelectedEvent evt)
 {
 }