What are the exact languages supported by the WPF in-built spell checking?

I understand only 4 languages are supported within WPF in-built spelling, English, German, French and Spanish are available. But is only en-US supported, how about en-GB?

Documentation on this topic in MSDN docs. seems spar开发者_开发百科se at best. Where can I locate exact details on the languages supported?

The reason I ask this is that I would like to add settings within my WPF app where you can select the language for the spell check or have an option for disabling the in-built feature. Within these options I would like to list the exact languages that are supported, whether it is en-US or en-GB etc.

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Only English, French, German and Spanish for now. You need to install the latter three with the .Net Language pack. You can also add some limited custom jargon to those languages (see this blog), but there is no way to add an entire dictionary.