I'm using a session in language en_us. When my session timeouts, i'm redirected to the login form. When i select another language (fr_fr) in this form, the session is re-opened, but in en_us. So that the language selected in the re-login form is not taken in account.
I don't know if it is a bug or a feature. Both should be fine, except that it should be easier to understand if there weren't any language selection box in the re-login form.