[KDE] Do any KDE/GTK/Mozilla theme/style combos allow one-click light/dark switching?

[ThorstenNY]

Hi:

I like to switch between Breeze and Breeze Dark themes depending on the time of day. This works great—just one click—for all Plasma apps, but it doesn’t work at all for GTK apps, in particular Firefox, which I care about most (in the GTK world.) The default Mozilla theme says that it respects OS/desktop settings, but that doesn’t seem to work on my system. (I run an up-to-date version of Kubuntu 20.10.)

In fact, I can’t seem to enable any dark theme for Firefox, Thunderbird, Chromium et al. (even manually, using Application Style → Gnome/GTK Application Style → Breeze-Noir-Dark-GTK) using system-settings.

The only option to turn FF and Thunderbird dark that worked for me was to use a dark theme in FF and Thunderbird, but that is super inconvenient, as I have to do it for each app separately.

Has anyone had success with affecting GTK app look and feel from KDE?

[ThorstenNY]

Okay, I’ve made some progress. I can now get Firefox, Thunderbird etc. to show a dark theme by enabling Application Style → Gnome/GTK Application Style → Breeze-Noir-Dark-GTK, but this only takes effect when I log out and back in again. (plasmashell --replace has no effect.)

Is there any command to restart the entire KDE desktop, with all settings?

I’d still like to be able to switch between light and dark using one option. I can’t believe this is impossible, especially considering that Firefox now appears to be the default browser in Kubuntu.