Different language for frontend and backend – not longer possible?

In a previous version it was possible to select different languages for the backend and the frontend, but I cannot find the second select field in the msls settings anymore (only the overall “blog language” one). Is this function not longer available or is there any way to activate it again? Would be very helpful, if the backend would remain in english, independently of the language that is used in the frontend in my case. ?? Thanks a lot!