bug#68766: 29.2; Windows dark/light mode changes does not reflect on Emacs Title bar/Scrollbar

[Stefan Kangas <stefankangas@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

> It's "by design", in the sense that this is how the Dark theme support
> is implemented in Emacs.  If someone submits changes to react to theme
> change immediately for all the frames, we can consider that for
> inclusion.

I think that would be a useful feature, indeed.

AFAIU, the point of light/dark mode for many users is that they want to
use different settings depending on the time of day.  This needs the
Emacs frame to react to it when the time switches (as most programs in
desktop environments like Gnome, or even macOS, do).

For example, Emacs on macOS already reacts automatically to light/dark
mode settings.  I believe this is provided by the toolkit itself,
without any changes in Emacs (or I missed them going in).

---

On a side note, I still don't think we have support for changing the
theme as well, do we?  This is the feature that auto-dark-mode provides.
In addition to changing the toolbar settings, I'd propose the new user
options `theme-dark' and `theme-light' indicating themes to switch to
when the desktop environment tells us that it's time.

This would be possible if the above new feature could also expose these
events to Lisp somehow.