/// <summary>
        /// user has selected or de-selected a content language
        /// </summary>
        public void ContentLanguagesSelectionChanged()
        {
            Logger.WriteEvent("Changing Content Languages");
            string l2 = null;
            string l3 = null;

            foreach (var language in _contentLanguages)
            {
                if (language.Locked)
                {
                    continue;                     //that's the vernacular
                }
                if (language.Selected && l2 == null)
                {
                    l2 = language.Iso639Code;
                }
                else if (language.Selected)
                {
                    l3 = language.Iso639Code;
                    break;
                }
            }

            //Reload to display these changes
            SaveNow();
            CurrentBook.SetMultilingualContentLanguages(l2, l3);
            CurrentBook.PrepareForEditing();
            _view.UpdateSingleDisplayedPage(_pageSelection.CurrentSelection);
            _view.UpdatePageList(true);            //counting on this to redo the thumbnails

            Logger.WriteEvent("ChangingContentLanguages");
            Analytics.Track("Change Content Languages");
        }