Change interface language

Hi,

thanks for your request. Your problem does not seem to be related to the "Language Switcher Extended" module, but is more a support requests for Drupal core.

I guess currently all the language switchers are only changin the content language? Or am I wrong?

No, I don't think so. When enabling the language module (no content translation) in Drupal you will have the possibility to add a language switcher and choose between different language detection.

There you basically need to select something. And Drupal / the browser needs to know which language is selected. This can be done with language prefix, custom domain per language, based on the browser language, per user session or based on the user account.

What you're describing sounds a bit like the user session. Then the language switcher block will append a GET parameter, e.g. `language=fr` into the URL of the other language. When you click on it it will change the interface language and from now on (when you don't switch the language again) the selected language will be carried with via your browser session.

But the "Language Switcher Extended" module tries to solve challenges, when you're working with translated content as well, or better when you have partially translated content and some of your nodes are not translated. It provides resolution techniques for the language switcher, so that the user will no experience undesired language changes and confusion.