From 6a94c1a59737783c282c4031555a289c28b961e4 Mon Sep 17 00:00:00 2001
From: Kilian Mio <86004375+Mikilio@users.noreply.github.com>
Date: Thu, 17 Aug 2023 10:27:17 +0200
Subject: [PATCH] fix(qt): allow theming for apps started by systemd (#4349)

---
 modules/misc/qt.nix | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/modules/misc/qt.nix b/modules/misc/qt.nix
index 554072e2f..2eb592615 100644
--- a/modules/misc/qt.nix
+++ b/modules/misc/qt.nix
@@ -128,7 +128,20 @@ in {
     };
   };
 
-  config = mkIf (cfg.enable && cfg.platformTheme != null) {
+  config = let
+
+    # Necessary because home.sessionVariables doesn't support mkIf
+    envVars = filterAttrs (n: v: v != null) {
+      QT_QPA_PLATFORMTHEME = if cfg.platformTheme == "gtk" then
+        "gtk2"
+      else if cfg.platformTheme == "qtct" then
+        "qt5ct"
+      else
+        cfg.platformTheme;
+      QT_STYLE_OVERRIDE = cfg.style.name;
+    };
+
+  in mkIf (cfg.enable && cfg.platformTheme != null) {
     assertions = [{
       assertion = cfg.platformTheme == "gnome" -> cfg.style.name != null
         && cfg.style.package != null;
@@ -141,16 +154,10 @@ in {
     qt.style.package = mkIf (cfg.style.name != null)
       (mkDefault (stylePackages.${toLower cfg.style.name} or null));
 
-    # Necessary because home.sessionVariables doesn't support mkIf
-    home.sessionVariables = filterAttrs (n: v: v != null) {
-      QT_QPA_PLATFORMTHEME = if cfg.platformTheme == "gtk" then
-        "gtk2"
-      else if cfg.platformTheme == "qtct" then
-        "qt5ct"
-      else
-        cfg.platformTheme;
-      QT_STYLE_OVERRIDE = cfg.style.name;
-    };
+    home.sessionVariables = envVars;
+
+    # Apply theming also to apps started by systemd.
+    systemd.user.sessionVariables = envVars;
 
     home.packages = (if cfg.platformTheme == "gnome" then
       [ pkgs.qgnomeplatform ]