set gtk theme in gsettings

overlays/sway.nix

@@ -1,4 +1,4 @@
-(final: pkgs: {
+(pkgs: _: {
   # bash script to let dbus know about important env variables and
   # propogate them to relevent services run at the end of sway config
   # see
@@ -16,4 +16,30 @@
       systemctl --user start pipewire pipewire-media-session xdg-desktop-portal xdg-desktop-portal-wlr
     '';
   };
+
+  # currently, there is some friction between sway and gtk:
+  # https://github.com/swaywm/sway/wiki/GTK-3-settings-on-Wayland
+  # the suggested way to set gtk settings is with gsettings
+  # for gsettings to work, we need to tell it where the schemas are
+  # using the XDG_DATA_DIR environment variable
+  # run at the end of sway config
+  configure-gtk = pkgs.writeTextFile {
+    name = "configure-gtk";
+    destination = "/bin/configure-gtk";
+    executable = true;
+    text =
+      let
+        schema = pkgs.gsettings-desktop-schemas;
+        datadir = "${schema}/share/gsettings-schemas/${schema.name}";
+      in
+      ''
+        export XDG_DATA_DIRS=${datadir}:$XDG_DATA_DIRS
+        gnome_schema=org.gnome.desktop.interface
+        gsettings set $gnome_schema gtk-theme '${pkgs.uservars.gtk_theme}'
+        gsettings set $gnome_schema icon-theme '${pkgs.uservars.icon_theme}'
+        gsettings set $gnome_schema cursor-theme '${pkgs.uservars.cursor_theme}'
+        gsettings set $gnome_schema color-scheme prefer-${pkgs.uservars.color.type}
+      '';
+  };
+
 })

user/theme.nix

@@ -71,6 +71,10 @@ with pkgs.uservars; {
     fira-code
     nerdfonts_fira_hack
     material-wifi-icons
-
   ];
+  home.activation = {
+    update_gtk = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
+      $DRY_RUN_CMD ${pkgs.configure-gtk}/bin/configure-gtk
+    '';
+  };
 }