/// <summary>
        /// sauvegarde les films en chambre d'isolation
        /// </summary>
        /// <param name="isolatedStorage"></param>
        private void saveFilms(IsolatedStorageFile isolatedStorage)
        {
            using (var isolatedStorageFileStream = isolatedStorage.OpenFile(XMLTags.FICHIER_FILMOTHEQUE, System.IO.FileMode.Create))
            {
                System.Xml.XmlWriterSettings settings = new System.Xml.XmlWriterSettings();
                settings.Indent = true;

                using (System.Xml.XmlWriter writer = System.Xml.XmlWriter.Create(isolatedStorageFileStream, settings))
                {
                    FilmWriter writerFilm = new FilmWriterWP7();
                    writerFilm.mXDoc = new XDocument();
                    writerFilm.mXDoc.Add(new XElement(XMLTags.FILMS));
                    foreach (Film f in listeFilms)
                    {
                        writerFilm.saveData(f, null);
                    }
                    writerFilm.mXDoc.Save(writer);
                }
            }
        }