* Use paintRect and plain colors instead of lightenRect and a weird
dimming factor.
* Update call sites to the new API
* Handle FP maths properly (i.e., floor coordinates & ceil dimensions at
the latest possible time).
* Fix border handling in the fill bar (make sure we actually honor it
when computin the x position, and that we won't overflow into it when
computing the width).
* Update docs
942ea70235