pantheon.gala: use smooth scroll events to handle mouse wheel in multitasking view

pkgs/desktops/pantheon/desktop/gala/default.nix

@@ -1,5 +1,7 @@
-{ lib, stdenv
+{ lib
+, stdenv
 , fetchFromGitHub
+, fetchpatch
 , nix-update-script
 , pantheon
 , pkg-config
@@ -38,11 +40,16 @@ stdenv.mkDerivation rec {
     sha256 = "1phnhj731kvk8ykmm33ypcxk8fkfny9k6kdapl582qh4d47wcy6f";
   };
 
-  passthru = {
-    updateScript = nix-update-script {
-      attrPath = "pantheon.${pname}";
-    };
-  };
+  patches = [
+    ./plugins-dir.patch
+    # Multitasking view: Don't use smooth scroll events to handle mouse wheel
+    # Avoid breaking the multitasking view scroll once xf86-input-libinput 1.2.0 lands
+    # https://github.com/elementary/gala/pull/1266
+    (fetchpatch {
+      url = "https://github.com/elementary/gala/commit/d2dcfdefdf97c1b49654179a7acd01ebfe017308.patch";
+      sha256 = "sha256-2lKrCz3fSjrfKfysuUHzeUjhmMm84K47n882CLpfAyg=";
+    })
+  ];
 
   nativeBuildInputs = [
     desktop-file-utils
@@ -73,15 +80,17 @@ stdenv.mkDerivation rec {
     mutter
   ];
 
-  patches = [
-    ./plugins-dir.patch
-  ];
-
   postPatch = ''
     chmod +x build-aux/meson/post_install.py
     patchShebangs build-aux/meson/post_install.py
   '';
 
+  passthru = {
+    updateScript = nix-update-script {
+      attrPath = "pantheon.${pname}";
+    };
+  };
+
   meta =  with lib; {
     description = "A window & compositing manager based on mutter and designed by elementary for use with Pantheon";
     homepage = "https://github.com/elementary/gala";