The code is very out-of-date by now, but check out the old Ubiquity project https://en.wikipedia.org/wiki/Ubiquity_(Firefox) https://en.wikipedia.org/wiki/Ubiqu

The code is very out-of-date by now, but check out the old Ubiquity project https://en.wikipedia.org/wiki/Ubiquity_(Firefox) https://en.wikipedia.org/wiki/Ubiquity_(Firefox) Before it died, they even had complex internationalization support that could handle different subject-verb-object orders and typed autocomplete.