// Ajouter ou retirer l'index de photo
        private void AddRemove_SlideShow(int photoId)
        {
            int index = SlideShowList.IndexOf(photoId);

            if (index == -1)
            {
                SlideShowList.Add(photoId);
            }
            else
            {
                SlideShowList.RemoveAt(index);
            }
        }
 private bool InSlideShow(int photoId)
 {
     return(SlideShowList.IndexOf(photoId) != -1);
 }