Detect "Suplemental language support" on Windows XP

I need a way to programatically determine if this checkbox in control panel is chec开发者_如何学运维ked (Windows XP):

Screenshot:

The checkbox is in Control Panel - Regional settings - Language - Supplemental language support - and is called "Install files for complex script and right-to-left languages".

It would be best to check for some related registry entry, but I do not know which one. Any ideas?

It seems to me that the same API which I describe in Detect if any right-to-left language is installed can be used to verify that the corresponding right-to-left languages are installed.