- Use lenses in core library
- Fix cursor cropping in render function where missing
- Deal with multi-column characters everywhere
- Implement 2-d text editing
- Write benchmarks for render on various primitive types
- Use Vector instead of List where sensible
- Implement region-to-view scrolling instead of point-to-view
  - to do this with lists, we need to know the height of each prim in
    the list so we can add them up to compute height ranges for each
    item. we could just make the user specify this, although we could
    also add a function to compute the (Maybe Int) height of a Prim and
    require that to be Just in the case of list elements
- Think about porting some widgets from vty-ui
- Think of better library name
- Support "suggested" vs "forced" attributes in Prim rendering