The previous "the endpoints are inclusive" comment seems confusing. It's true
that the bounding box's max X equals the right-most coordinate, which suggests
<= instead of <, but that node's coordinate is itself exclusive. Consider the
solid 1-pixel square: (0, 0), (64, 0), (64, 64), (0, 64) in fixed.Point26_6
coordinates. The right-most coordinate is 64, and the bounding box's max X
equals 64, but rasterizing that square only affects sub-pixels up to but not
including 64.

Instead, it seems accurate to follow the fixed.Rectangle26_6 description, in
that the max values are exclusive.