Fall back to old Gnome prefer-dark if first try fails

settings/appearance/appearance.go

@@ -1,4 +1,7 @@
 // Package appearance is a helper package for reading appearance settings.
 package appearance
 
-const appearanceNamespace = "org.freedesktop.appearance"
+const (
+	appearanceNamespace     = "org.freedesktop.appearance"
+	gnomeInterfaceNamespace = "org.gnome.desktop.interface"
+)

settings/appearance/color.go

@@ -23,7 +23,7 @@ const (
 func GetColorScheme() (ColorScheme, error) {
 	value, err := settings.ReadOne(appearanceNamespace, "color-scheme")
 	if err != nil {
-		return NoPreference, err
+		return getGnomeInterfacePreference() // Fallback if new interface does not exist.
 	}
 
 	result := value.(uint32)
@@ -74,3 +74,17 @@ func GetAccentColor() (*color.RGBA, error) {
 		A: uint8(alpha),
 	}, nil
 }
+
+func getGnomeInterfacePreference() (ColorScheme, error) {
+	value, err := settings.ReadOne(gnomeInterfaceNamespace, "color-scheme")
+	if err != nil {
+		return NoPreference, err
+	}
+
+	result := value.(string)
+	if result == "prefer-dark" {
+		return Dark, nil
+	}
+
+	return NoPreference, nil
+}