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Comment by bdjsiqoocwk | Hacker News Reader

Very OT, but I don't know where else to turn to because the Reddit community has been of no help.

I used i3 and I absolutely love the way it feels. However I would like to configure it in a way that I can press a button and every app turns into dark mode. My main apps (Firefox, vscode) have an option to say "use system theme" i.e. if the os is dark, theme this app dark. Great! The problem is I don't know how to set the system theme. And every time I've asked around, I see people respond with GTK, QT and what not. I don't have those, I have i3.

Help?

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If it is a gtk app it will use the gtk mechanism, if it is a qt app it will use the qt mechanism, otherwise your in luck, you get to use the native X11 mechanism.

gtk: hell if I know, the web sez there are css files, and there are probably some gnome tools to set the theme.

qt: no clue. and the web was unhelpful

native X11: now we are talking I know this one, X11 provides a database that applications can use for configuration and design. The main interface is the xrdb command. and all good application should include the pertinent points of their call tree to get you started in theming them. http://man.openbsd.org/xrdb

What those people told you is correct, and "I don't have those, I have i3" is incorrect. Stop ignoring them.

I'm not ignoring. I still don't know how do I enable dark mode. If you have the answer, would you kindly help?

i3 is just a window manager. It's not a UI toolkit. It doesn't control how apps render UI.

GTK and QT are UI toolkits and do control how apps render UI. Your apps will use GTK and QT even if you use i3 to manage the windows.

You might be confusing GTK with Gnome and QT with KDE, each of which has its own window manager.

so you're saying to get gtk apps to switch to dark mode, you'd find the gtk setting for dark mode? and the same for qt?

Yes, for example check "gsettings set org.gnome.desktop.interface gtk-theme" for the gtk apps.

See but this is the kind of responses that confuse me.

What does that mean "gtk apps"? Is firefox a "gtk app"? Is vscode a "gtk app"? etc.

Check the dependencies. If it depends on libgtk, it's a gtk app. libQt, is a qt app. There maybe rare other situations (Tk, plain xlib, fltk, etc.)

This will get you 99%, but there are exceptions. I.e. Firefox is linked against GTK, but paints its own widgets with custom theming anyways. Telegram is linked against Qt, but has it's own theming/dark mode too.

You seem like you know what you're talking about, help please? https://news.ycombinator.com/item?id=40583867

As in this post

https://askubuntu.com/questions/769417/how-to-change-global-...

I ran gsettings set org.gnome.desktop.interface gtk-theme 'Adwaita-dark' and firefox isn't in dark mode, despite the fact that i have firefox configured to use the system theme and firefox is on GTK according to google.

Help again?

When you set dark mode in the current gnome (with support for dark mode), the following will be set:

    org.gnome.desktop.interface color-scheme 'prefer-dark'

Valid values are “default”, “prefer-dark”, “prefer-light”.

    org.gnome.desktop.interface gtk-theme '(your-theme)-dark'

This is the one you have set.

    $ gsettings get org.gnome.desktop.interface color-scheme
    No such key “color-scheme”

Debian 11. Is it because it's old-ish?

Oh, Gnome 3.38. I'm not sure that version even supported dark mode, only dark themes. I won't comment on aging of Debian ;).

Btw, what version of Firefox are you using? Debian comes with ESR, so chances are, that firefox' "ui.systemUsesDarkTheme = 1" still works (it doesn't in newer releases).

I have 102.6.0esr (came with the OS) and I also installed 126.0. Neither of them has has `ui.systemUsesDarkTheme`.

So anyway do you think that if I upgrade to the latest Debian, your gtk command line will work?

It should; it does on the gnome install: https://youtu.be/Vpkz89gN9zk

Oh man that's such a nice feature.

I guess now I have a reason to upgrade.

Thank you!

And you know, this

> You might be confusing GTK with Gnome and QT with KDE, each of which has its own window manager.

Just cleared up a lot of confusing in my mind. Thank you.

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