bug#57639: [PATCH] Add new command 'toggle-theme'

[Lars Ingebrigtsen]

Philip Kaludercic <philipk@posteo.net> writes:

> One last additional, I've added a property to all the themes indicating
> that they are colour schemes.  This would make it easier to toggle
> between dark and light modes if multiple themes are enabled of which
> only one is a colour theme:

Makes sense.  One thing that occurred to me now that I didn't think of
before is:

>  (deftheme adwaita
>    "Face colors similar to the default theme of Gnome 3 (Adwaita).
>  The colors are chosen to match Adwaita window decorations and the
> -default look of the Gnome 3 desktop.")
> +default look of the Gnome 3 desktop."
> +  :background-mode 'light
> +  :kind 'color-scheme)

Is this backwards compatible, and is that something we need to care
about?  I know that some (many?) themes are also distributed outside of
Emacs, and should work under a range of Emacs versions.  I don't think
extending `deftheme' in this way would be backwards compatible, though,
even if it makes sense from a language design point of view.