WPF XAML StringFormat DateTime: Output in wrong culture?

Please see my answer on StringFomat Localization problem

To apply the solution mentioned at http://tinyurl.com/b2jegna do the following:

(1) Add a Startup event handler to the Application class in app.xaml:

<Application x:Class="MyApp"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    ...
    Startup="ApplicationStartup">

(2) Add the handler function:

private void ApplicationStartup(object sender, StartupEventArgs e)
{
    FrameworkElement.LanguageProperty.OverrideMetadata(
        typeof(FrameworkElement),
        new FrameworkPropertyMetadata(XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
}

WPF strings should then be formatted correctly according to culture.