Re:

[Eli Zaretskii]

> From: Davin Pearson <davin.pearson@gmail.com>
> Date: Mon, 20 Dec 2021 15:29:04 +1300
> 
> I was wondering if you could make the following improvement to
> GNU Emacs: Make it so that fonts with a nil for background-colour
> have the fontification of the inner symbols shines through
> to appear over higher layers, like so:
> 
> *abc* is fontified as a blue foreground with nil background
> 
> "*abc*" is fontified in light blue background with a black foreground
> but should appear with a light blue background and a blue foreground.

AFAIU, what you are asking basically goes against the way faces are
implemented in Emacs: when Emacs merges two faces, if both of them
specify the foreground color, one of them will "win", and the
foreground of the other will be ignored.