I've long wanted an extension that rather than translating a full page, translates just the word under the mouse -- ideally without causing any reflow -- so that I could try struggling through reading a foreign-language page, incrementally learning the words as I progress.
Anyone seen such a thing?
It seems it could also mix well with this 'Polyglot' approach, by throwing in some percentage of pre-translated words, or remembering words known/unknown and differentially displaying those.