Detail colour support available about hint HOT 1 OPEN

The current version 2.0 HINT file format does not support any color.

Color support is planed for future versions. Adding color support to the file format is not the difficult part. The design of primitives, that are flexible and can be integrated without too much effort into TeX and most importantly LaTeX is the challenging part.
Just reproducing the PDF primitives is an option, but possibly not the best.

Here is a proposal for discussion:

\HINTbackground
Changes the background of the enclosing box.
If no background color is given the box is transparent.
The page background can be specified in the page template.
If multiple background colors are specified in the same box the last one wins.
Nested boxes can have different background colors.

\HINTforeground
Changes the color of glyphs and rules.
The effect is limited to the enclosing hbox or paragraph.
The effect extends to sub-boxes or sub-paragraphs.
If no color is given the color black is used.
If multiple colors are specified within the same box or paragraph,
every color is used for all glyphs or rules following the color
specification up to the following color specification or the end of
the box or paragraph that contains the color specification.

from hint.