// 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.
FrameworkElement.LanguageProperty.OverrideMetadata(
  typeof(FrameworkElement),
  new FrameworkPropertyMetadata(System.Windows.Markup.XmlLanguage.GetLanguage(
	  System.Globalization.CultureInfo.CurrentCulture.IetfLanguageTag)));