Tying language selected at login with UI language

Hi I’m wondering if there’s a way to interlock login form language
[through query string - &language=xx] page/form to logging users
UI Language.

Please DO Enlight me.

Have a nice day!

what do you mean?

I have .htaccess rewrite rule adding query string where piwik is installed &language=en [or setting ?language=en when there’s none and passing typed manually language=xx]
And I’d like that language to be forced on UI of signing in user.

Simply
I’d like to determine dashboard language at login with query string parameter [overwriting/ignoring what’s in piwik_user_language table]

BTW: Why Language Switcher can’t be turned off ?

Guess I’ll meddle with authenticateAndRedirect for a while.
No luck there, searching further

Now things are at : How to pass language=xx beyond login page.

If you know the username, you can configure the langauge for a user to use via the API
http://piwik.org/docs/analytics-api/reference/#LanguagesManager
LanguagesManager.setLanguageForUser (login, languageCode)

does it help?