I'm proofreading an old French book on Wikisource, and at the moment, the spellchecker is in English. I'd like a way to change the spellchecker for this site only. At the moment I would have to change to French and then change back when I finished, and I can't find anything else on this topic here or on Google. Is this currently possible? If not, would it be possible to create an addon to do this? Any advice on the most useful APIs to use for such an addon would be very helpful. Cheers!