We got all Windows cultures with the Command:
CultureInfo[] allCultures = CultureInfo.GetCultures(CultureTypes.SpecificCultures);     
The same list is in the
Language Property of the System.Windows.Forms.Form.
Is it possible to add own elements into this list?
Maye be, wee need "customer1-DE", "customer2-DE"...

There isn't a way to add it to "CultureInfo.GetCultures", but there also shouldn't be a need.

This returns the operating system defined cultures.  If you're adding your own, specific culture, just create the CultureInfo (or modify the existing german culture), and save the CultureInfo in your application.  You don't need to add it to "CultureInfo.GetCultures", just make your CultureInfo and use it.

---

Reed Copsey, Jr. - http://reedcopsey.com