bug#64799: [PATCH] Add 'project-prompt-key' face

[Eli Zaretskii]

> Cc: 64799@debbugs.gnu.org
> From: Protesilaos Stavrou <info@protesilaos.com>
> Date: Wed, 26 Jul 2023 07:50:26 +0300
> 
> >>> But a user option to change how the prompt text is constructed -- why
> >>> not. E.g. one defaulting to "[%s] %s".
> >> 
> >> Is there really such a wide range of options that users might be
> >> interested in here?
> >
> > Protesilaos wanted to use a different format?
> 
> For my use, and Emacs 28+, I want this:
> 
>     (format "%s %s"
>                (propertize (key-description key) 'face 'project-prompt-key)
>                label)
> 
> The reason I mentioned the possibility of a user option is because
> without the square brackets the bold face will not have the same effect
> as the current design.  The square brackets help add structure and make
> it easier to identify the keys.  The use of 'bold' without the square
> brackets may make it more difficult for users to spot the keys.

Beware: the 'bold' face changes the metrics of the font glyphs (wrt
the 'medium' variant), and at least with some fonts could cause a
small 1- or 2-pixel vertical resize of the mini-window, which is
generally distracting and even annoying.