> That would mean the indicator will inherit the background color of any
> face of the last character on the line.  Is that the intent, and what
> users will want?

That was the behavior of fci-mode, and I never received a request for
different
behavior.

Please note that that's already what this implementation does with the
stretch glyph.  If you think
that behavior is wrong, then the treatment of the stretch glyph should be
changed as well.