Setting Culture (en-IN) globally in WPF application

Thread.CurrentThread.CurrentCulture = 
    System.Globalization.CultureInfo.GetCultureInfo("en-IN");

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

This will switch the default language for the entire application. You’ll want to use this only in startup code as this setting can be applied only once per application. You can still override individual forms when necessary as below

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

All WPF elements include a Language property that can be assigned and determines the Culture that is used for formatting.

Reference

I think you will need to add the following.

Thread.CurrentThread.CurrentCulture = new CultureInfo("en-IN");
Thread.CurrentThread.CurrentUICulture = new CultureInfo("en-IN");
FrameworkElement.LanguageProperty.OverrideMetadata(typeof(FrameworkElement), new FrameworkPropertyMetadata(
            XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));

Read more here:

http://www.west-wind.com/weblog/posts/2009/Jun/14/WPF-Bindings-and-CurrentCulture-Formatting

Just to give you an example, this is how I initialize the Culture in my program, based on the user setting, but you can simply replace UserSettings.DefaultCulture and UserSettings.Default.UICultrue with your wanted Culture.

private static void InitializeCultures()
{
    if (!String.IsNullOrEmpty(UserSettings.Default.Culture))
    {
        Thread.CurrentThread.CurrentCulture = new CultureInfo(UserSettings.Default.Culture);
    }
    if (!String.IsNullOrEmpty(UserSettings.Default.UICulture))
    {
        Thread.CurrentThread.CurrentUICulture = new CultureInfo(UserSettings.Default.UICulture);
    }

    FrameworkElement.LanguageProperty.OverrideMetadata(typeof(FrameworkElement), new FrameworkPropertyMetadata(
        XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
}

For me just works, if i put this code to the OnStartup overrided method:

public partial class App : Application
{
      public App()
      {                
      }

      protected override void OnStartup(StartupEventArgs e)
      {
          var vCulture = new CultureInfo("de-DE");

          Thread.CurrentThread.CurrentCulture = vCulture;
          Thread.CurrentThread.CurrentUICulture = vCulture;
          CultureInfo.DefaultThreadCurrentCulture = vCulture;
          CultureInfo.DefaultThreadCurrentUICulture = vCulture;

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

          base.OnStartup(e);
      }
}