Установка CultureInfo для всего приложения

public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs eventArgs)
    {
        var russianCultureInfo = new CultureInfo("ru-RU");
        Thread.CurrentThread.CurrentCulture = russianCultureInfo;
        Thread.CurrentThread.CurrentUICulture = russianCultureInfo;
        FrameworkElement.LanguageProperty.OverrideMetadata(typeof(FrameworkElement),
            new FrameworkPropertyMetadata(
                XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
        base.OnStartup(eventArgs);
    }
}

// 3,14
string x = 3.14.ToString(CultureInfo.CurrentCulture);
 
// 26.02.2018 0:00:00
string y = DateTime.Today.ToString(CultureInfo.CurrentCulture);
 
// понедельник
string z = Thread.CurrentThread.CurrentCulture.DateTimeFormat.GetDayName(DateTime.Today.DayOfWeek);
 
// Февраль
string a = Thread.CurrentThread.CurrentCulture.DateTimeFormat.GetMonthName(DateTime.Today.Month);

public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs eventArgs)
    {
        var russianCultureInfo = new CultureInfo("ru-RU")
        {
            NumberFormat = {NumberDecimalSeparator = "."}
        };
        Thread.CurrentThread.CurrentCulture = russianCultureInfo;
        Thread.CurrentThread.CurrentUICulture = russianCultureInfo;
        FrameworkElement.LanguageProperty.OverrideMetadata(typeof(FrameworkElement),
            new FrameworkPropertyMetadata(
                XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
        base.OnStartup(eventArgs);
    }
}