Highlight idioms we haven't seen before
Just like we get highlighted in yellow "new word", it would be really nice if we could get tricky idioms highlighted as "new phrase" or "new idiom". Sometimes there are some really hard idioms, that if I didn't peek, or even did peek, I would still have never known what the words meant. Learning new idioms are often like learning new words; you have to be told what they are meant, because the first time you see them, you will have no idea. It would be great if this could happen.
Maybe this could be worked on in the hackathon??? :)