WPF Culture App Startup

    public partial class App : Application
    {
        protected override void OnStartup(StartupEventArgs e)
        {
            var cult = CultureInfo.GetCultures(CultureTypes.AllCultures)
                .FirstOrDefault(t=>t.Name == "en-GB");

            FrameworkElement.LanguageProperty.OverrideMetadata(
                  typeof(FrameworkElement),
                  new FrameworkPropertyMetadata(
                     XmlLanguage.GetLanguage(
                     cult.IetfLanguageTag)));

            base.OnStartup(e);
        }
    }