"Berto" wrote: .....
Maybe the local links to Commons could have "?uselang=" at the end of the URLs?
Yes! http://commons.wikimedia.org/?uselang=fr works. Is it an acceptable practice? By the way... this thing alone would have interwiki links mantain a stable interface, if put on the main soft engine... I do not really think that it would cost much work...
I'd want this on the software too.
This is not what I want, but it's better than nothing. The good thing would be a dedicated page there, that would upload images to commons, as the old one did. Any time you ask a user to click once more you loose traffic. Things must be as simple as possible.
The 'Subir este archivo' link on the tool section sends you to http://commons.wikimedia.org/wiki/Special:Upload?uselang=es However, this message will still show from other links.
As how we did it, Alphax, we decided it on a poll http://es.wikipedia.org/wiki/Wikipedia:Votaciones/2006/Cambiar_pol%C3%ADtica... and then asked it on bugzilla :-)
About language selecting on login, commons had recently set a lenguage selector on http://commons.wikimedia.org/wiki/Special:Userlogin so you can easily change the language on the login. This will stay when as your preference when you create an account (sorry, pms is not on the list, but you can always use the ?uselang=pms).