This seems like an OS feature that it should expose to the browser, working with
registerContentHandler(). Especially given read-write access to the file system, I agree this would be useful for a range of apps.
It makes sense to me to use
registerContentHandler() to deal with local file types, but different platforms have slightly different conventions about how identifying local file types works, no? More to the point, there is still not much uptake or apparent interest from many browsers for