David Kastrup wrote:

<< currently involved with programming a footnote package, I was trying
to get a clue about just when to insert \color@begingroup and
\color@endgroup >>

There is a fairly **efficient** 'hack' solution based on the idea that
the "size" of a font declaration can be understood by a dvi-driver
to (in certain cases) force the color of the font.  Since almost
nobody is going to hack a driver for this purpose, one would probably
implement this idea by dvi post-processing. Not hard. No new fonts
needed, just some slightly weird font declarations.

Laurent S.