I'm concerned about the case where the intl extension is not installed because (a) there may be some sites where it's difficult for the user to install/enable it and (b) I want to make it as easy as possible to use the application. So if somebody's wanting to use a genuine language xy, then I want to know whether it's possible, or whether I should fall back to their next, genuine, choice. As things stand, Windows will just tell me that, yes, it's managed to set the locale to xy, when in fact it hasn't.