bug#46177: 27.1; Display problem with minibuffer overlay when using display property

[Clemens]

> Use a face which explicitly overrides every attribute of minibuffer
> prompt face, I guess?

As far as I understand I would have to loop through the overlay string, 
too and apply those face adjustments to every of those display property 
strings. I think then I can also just inline them like in my shown 
example which avoid this issue in the first place.

> > (set-face-attribute 'minibuffer-prompt nil :foreground "purple")
> > (minibuffer-with-setup-hook
> >       (lambda ()
> >         (overlay-put
> >          (make-overlay (point-max) (point-max) nil t t)
> >          'after-string
> >          (concat " from"
> >                    (propertize " world"
> >                                'display
> >                                " minibuffer"))))
> >     (read-string "Hello"))
> >
> >
> > Even with the " from" string between the string defined in the display
> > property gets the prompt face applied.
>
> Because " minibuffer" is a display string, and its buffer position is
> still EOB.  That it has the " from " string in the overlay property
> before it doesn't change the buffer position whose face affects the
> display string.

Because the " minibuffer" string follows the non affected " from" string
this is unexpected from a caller/UI viewpoint IMO. I don't understand 
the underlying reasoning for this but if you don't think there is 
something to fix here, I will accept that and continue using my workaround.