bug#48669: Inconsistent overlay placement between minibuffer-message and set-minibuffer-message

["João Guerra" <joca.bt@gmail.com>]

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`minibuffer-message' and `set-minibuffer-message' place the overlay
containing the message slightly differently, resulting in a different
behaviour when there are other overlays present at the end of the
minibuffer.

The overlay created by `minibuffer-message' always gets added to the
end of the minibuffer.
The overlay created by `set-minibuffer-message' also gets added to the
end of the minibuffer, but its properties make it so that it is shown
before other overlays at the position.
This is particularly important when the user uses packages that add
overlays to the minibuffer, such as vertical completion packages like
selectrum, vertico, and others.
The way `set-minibuffer-message' configures the overlays makes it so
that the overlay is displayed before the other overlays, which I
believe is more compatible with external packages (see attached image
for a visual example).

Would it make sense to change this behaviour (i.e. overlay
configuration) so that it is consistent in both functions?

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