bug#32344:

[Juri Linkov]

> Forgot the screenshots.

So nice looking screenshot, thanks.

But I wonder if you could just replace add-text-properties with
add-face-text-property?  It will keep your previous text properties
and will just merge them with the comint-highlight-input face.

So when the face comint-highlight-input is customized to have
no face attributes, add-face-text-property will do nothing.

But it would be more nice to change the default value of the face
comint-highlight-input to some light-grey background (it seems
a new face attribute ':extend' is not needed here).
Then add-face-text-property will add this background
to your fontified comint input.

PS: would other modes benefit from fontifying the input
with their syntax.  In particular, I don't understand
why the input is not fontified using emacs-lisp-mode
in the minibuffer of ‘M-:’ (‘eval-expression’)