kde: add applicationStyle and widgetStyle options (#2018)

Closes: https://github.com/nix-community/stylix/issues/2017
Link: https://github.com/nix-community/stylix/pull/2018

Co-authored-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
Reviewed-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
Reviewed-by: Ian Ressa <ianressa@umich.edu>

modules/kde/hm.nix

@@ -176,10 +176,10 @@ let
     mergeWithImage
       {
         kwinrc."org.kde.kdecoration2".library = cfg.decorations;
-        plasmarc.Theme.name = "default";
+        plasmarc.Theme.name = cfg.applicationStyle;
 
         kdeglobals = {
-          KDE.widgetStyle = "Breeze";
+          KDE.widgetStyle = cfg.widgetStyle;
           General.ColorScheme = colorschemeSlug;
         };
       }
@@ -355,6 +355,21 @@ in
         imperatively applying the window decoration via the System Settings app.
       '';
     };
+    widgetStyle = lib.mkOption {
+      type = lib.types.str;
+      default = "Breeze";
+      description = ''
+        The library for the widgets styles.
+
+        Widget styles other than default `Breeze` may not be compatible with
+        stylix.
+      '';
+    };
+    applicationStyle = lib.mkOption {
+      type = lib.types.str;
+      default = "default";
+      description = "The library for the application style.";
+    };
   };
 
   config =

modules/kde/testbeds/kde.nix

@@ -1,7 +1,21 @@
-{ lib, ... }:
+{ lib, pkgs, ... }:
 {
   config = {
     stylix.testbed.ui.graphicalEnvironment = "kde";
+
     services.displayManager.autoLogin.enable = lib.mkForce false;
+
+    home-manager.sharedModules = lib.singleton {
+      stylix.targets.kde = {
+        enable = true;
+        applicationStyle = "Utterly-Round";
+        widgetStyle = "Darkly";
+      };
+      home.packages = with pkgs; [
+        darkly
+        darkly-qt5
+        utterly-round-plasma-style
+      ];
+    };
   };
 }