var cultureName = CultureInfo.CurrentCulture.Name;
        
FrameworkElement.LanguageProperty.OverrideMetadata(
   typeof(FrameworkElement),
   new FrameworkPropertyMetadata(
   XmlLanguage.GetLanguage(cultureName)));
 
Thread.CurrentThread.CurrentUICulture = CultureInfo.CurrentCulture;

1253 of <%= App.Configuration.CommentMaxLength %> characters

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 /// <summary>
        /// Event that fires on application startup
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void OnStartup(object sender, StartupEventArgs e)
        {
            //Uri uri = new Uri("pack://application:,,,/Views/MainWindow.xaml", UriKind.RelativeOrAbsolute);
            //Application.Current.StartupUri = uri;
            try
            {
 
 
                // Ensure the current culture passed into bindings 
                // is the OS culture. By default, WPF uses en-US 
                // as the culture, regardless of the system settings.
                try
                {
                    // per http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo.ietflanguagetag(v=vs.110).aspx
 
                    var cultureName = CultureInfo.CurrentCulture.Name;
                    FrameworkElement.LanguageProperty.OverrideMetadata(
                        typeof(FrameworkElement),
                        new FrameworkPropertyMetadata(
                            XmlLanguage.GetLanguage(cultureName)));
                }
                catch (Exception ex)
                {
                    ex.PreserveExceptionDetail();
                    throw;
                }
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IetfLanguageTag 

this.Language = XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag);

      var cultureName = CultureInfo.CurrentCulture.Name;

    App()
        {
            // 3) Force just one copy to run
            try
            {
 
                // Setup unhandled exception handlers
                #region Handlers For Unhandled Exceptions
                // anything else to do on startup can go here and will fire after the base startup event of the application
                // First make sure anything after this is handled
                // Creates an instance of the class holding delegate methods that will handle unhandled exceptions.
                CustomExceptionHandler eh = new CustomExceptionHandler();
 
                AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(eh.OnAppDomainException);
 
                // this ensures that any unhandled exceptions bubble up to a messagebox at least
                Dispatcher.CurrentDispatcher.UnhandledException += new DispatcherUnhandledExceptionEventHandler(eh.OnDispatcherUnhandledException);
 
                #endregion  Handlers For Unhandled Exceptions
 
 
                this.ForceSingleInstance();
 
 
                this.Startup += this.OnStartup;
                this.Exit += this.OnExit;
                this.LoadCompleted += this.OnLoadCompleted;
 
 
                CableStay.Instance.Wire(App.AppDisplayName, false);
 
                this.ShutdownMode = ShutdownMode.OnExplicitShutdown;
 
                InitializeComponent();
 
 
 
            }
            catch (Exception ex)
            {
                ex.PreserveExceptionDetail();
                throw;
            }
        }