bug#43381: 27.1.50; Maybe wrong cursor FG color in NS port

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: alan@idiocy.org,  43381@debbugs.gnu.org,  dale@codefu.org
> Date: Thu, 17 Sep 2020 17:06:31 +0200
> 
> The character under point will have the cursor colour as the
> background colour, and it doesn't matter what the foreground colour
> of that character is: Today the foreground colour (when the cursor
> is over the character) is the character's background colour, but the
> proposal is to change that to use the default face's background
> colour instead.

I understand.  The result will be that every character under cursor
will look the same regardless of its original face colors.  Which is
both losing information and different from the face-merging we do
everywhere else.

The original problem, AFAIU, was not that we behave as we do, but that
the result is almost illegible in some situations.  The solution to
that doesn't have to be what you propose, it can be something else,
which doesn't ignore our usual face-merging.  We just need to use a
mechanism we have for this purpose: the distant-foreground color of a
face.