Light and dark appearance

GNOME stores the user's preferred color scheme in org.gnome.desktop.interface as color-scheme. Gnoblin reports preference changes to Lua config, so compositor rules can follow the same choice as applications.

Set the preference in GNOME Settings → Appearance, or with gsettings:

gsettings set org.gnome.desktop.interface color-scheme prefer-dark

What follows the setting

GTK 4 and libadwaita apps use this preference to choose their light or dark appearance. GTK 3 apps commonly follow the gtk-theme setting, such as Adwaita or Adwaita-dark. The preference does not force every application to change: some apps use their own theme controls, while some non-GTK apps choose to read color-scheme themselves.

Gnoblin does not pick an application theme. It makes the desktop preference available to Lua configs, which can update compositor styling and settings for shells or apps that opt in.

Follow the preference in window rules

Add a later rule for the selected palette. The example keeps all rules already loaded, then replaces the window-rule list with the current palette each time GNOME reports a change:

local base_rules = gnoblin.snapshot()["window-rules"] or {}

gnoblin.on("gnoblin.appearance.color-scheme-changed", function(event)
    local rules = {}
    for i, rule in ipairs(base_rules) do rules[i] = rule end

    local border = event.color_scheme == "prefer-dark" and "#aab2bd99" or "#35405299"
    rules[#rules + 1] = {
        match = {type = "window"},
        corners = {border_width = 1, border_color = border},
    }
    gnoblin.configure {window_rules = rules}
end)

The example takes the snapshot while the config loads, because gnoblin.snapshot() raises an error at run time. Inside the handler, gnoblin.configure returns an Operation that succeeds when the compositor commits the rules.

The event reports changes after the subscription starts; it does not replay the current preference. Add an initial window rule to the config if you want a palette before the first change event. Other values use the light palette in this short example; branch on default separately if your shell has its own default colors.

See Lua events for the event fields and window effects for border, shadow and blur options.