Currently it's only possible to review ahead if there's at least one review due.  The user does that review, and is then asked if they'd like to continue with reviews that aren't due.

They should have this ability even if there are no reviews overdue.

ugh.

Eg. should be able to select a bunch at once and marked them as "known" or "unknown"

Right now after studying it goes straight back to the review screen.  It would be nice to instead see a new screen showing what you learned during the lesson and how you improved (or not!)

todo: Figure out how to best represent learning progress using a graph

For crash-reporting/feedback/user metrics

Add an option to display the radicals for each Kanji in different colors