pantheon.elementary-session-settings: Various simplifications

* Remove default-elementary-dockitems.desktop as it is not useful with the new dock.
* See https://github.com/GNOME/gtk/blob/4.16.12/gtk/gtksettings.c for gtk-4.0/settings.ini.
* With systemd managed session the required components are actually managed by systemd.
* After the above changes there is no more need to install the script in libexec.

nixos/modules/services/x11/desktop-managers/pantheon.nix

@@ -232,7 +232,8 @@ in
       ])) config.environment.pantheon.excludePackages;
 
       # Settings from elementary-default-settings
-      environment.etc."gtk-4.0/settings.ini".source = "${pkgs.pantheon.elementary-default-settings}/etc/gtk-4.0/settings.ini";
+      # GTK4 will try both $XDG_CONFIG_DIRS/gtk-4.0 and ${gtk4}/etc/gtk-4.0, but not /etc/gtk-4.0.
+      environment.etc."xdg/gtk-4.0/settings.ini".source = "${pkgs.pantheon.elementary-default-settings}/etc/gtk-4.0/settings.ini";
 
       xdg.mime.enable = true;
       xdg.icons.enable = true;

pkgs/desktops/pantheon/desktop/elementary-session-settings/default.nix

@@ -5,7 +5,6 @@
 , desktop-file-utils
 , gettext
 , pkg-config
-, writeScript
 , gnome-keyring
 , gnome-session
 , wingpanel
@@ -21,74 +20,12 @@
 }:
 
 let
-
-  #
-  # ─── ENSURES PLANK GETS ELEMENTARY'S DEFAULT DOCKITEMS ────────────────────────────
-  #
-
-  #
-  # Upstream relies on /etc/skel to initiate a new users home directory with plank's dockitems.
-  #
-  # That is not possible within nixos, but we can achieve this easily with a simple script that copies
-  # them. We then use a xdg autostart and initialize it during the "EarlyInitialization" phase of a gnome session
-  # which is most appropriate for installing files into $HOME.
-  #
-
-  dockitems-script = writeScript "dockitems-script" ''
-    #!${runtimeShell}
-
-    elementary_default_settings="${elementary-default-settings}"
-    dock_items="$elementary_default_settings/etc/skel/.config/plank/dock1/launchers"/*
-
-    if [ ! -d "$HOME/.config/plank/dock1" ]; then
-        echo "Instantiating default Plank Dockitems..."
-
-        mkdir -p "$HOME/.config/plank/dock1/launchers"
-        cp -r --no-preserve=mode,ownership $dock_items "$HOME/.config/plank/dock1/launchers/"
-    else
-        echo "Plank Dockitems already instantiated"
-    fi
-  '';
-
-  dockitemAutostart = writeText "default-elementary-dockitems.desktop" ''
-    [Desktop Entry]
-    Type=Application
-    Name=Instantiate Default elementary dockitems
-    Exec=${dockitems-script}
-    StartupNotify=false
-    NoDisplay=true
-    OnlyShowIn=Pantheon;
-    X-GNOME-Autostart-Phase=EarlyInitialization
-  '';
-
-  common-export = ''
-    # gnome-session can find RequiredComponents for `pantheon` session (notably pantheon's patched g-s-d autostarts)
-    export XDG_CONFIG_DIRS=@out@/etc/xdg:$XDG_CONFIG_DIRS
-
-    # Make sure we use our gtk-3.0/settings.ini
-    export XDG_CONFIG_DIRS=${elementary-default-settings}/etc:$XDG_CONFIG_DIRS
-
-    # * gnome-session can find the `pantheon' session
-    # * use pantheon-mimeapps.list
-    export XDG_DATA_DIRS=@out@/share:$XDG_DATA_DIRS
-  '';
-
-  executable = writeScript "pantheon" (common-export + ''
-    # Start pantheon session. Keep in sync with upstream
-    exec ${gnome-session}/bin/gnome-session --session=pantheon "$@"
-  '');
-
-  executable-wayland = writeScript "pantheon-wayland" (common-export + ''
-    # Start pantheon-wayland session. Keep in sync with upstream
-    exec ${gnome-session}/bin/gnome-session --session=pantheon-wayland "$@"
-  '');
-
   # Absolute path patched version of the upstream xsession
   xsession = writeText "pantheon.desktop" ''
     [Desktop Entry]
     Name=Pantheon
     Comment=This session provides elementary experience
-    Exec=@out@/libexec/pantheon
+    Exec=${gnome-session}/bin/gnome-session --session=pantheon
     TryExec=${wingpanel}/bin/io.elementary.wingpanel
     Icon=
     DesktopNames=Pantheon
@@ -99,7 +36,7 @@ let
     [Desktop Entry]
     Name=Pantheon (Wayland)
     Comment=This session provides elementary experience
-    Exec=@out@/libexec/pantheon-wayland
+    Exec=${gnome-session}/bin/gnome-session --session=pantheon-wayland
     TryExec=${wingpanel}/bin/io.elementary.wingpanel
     Icon=
     DesktopNames=Pantheon
@@ -148,15 +85,6 @@ stdenv.mkDerivation rec {
     mkdir -p $out/share/applications
     cp -av ${./pantheon-mimeapps.list} $out/share/applications/pantheon-mimeapps.list
 
-    # instantiates pantheon's dockitems
-    cp "${dockitemAutostart}" $out/etc/xdg/autostart/default-elementary-dockitems.desktop
-
-    # script `Exec` to start pantheon
-    mkdir -p $out/libexec
-    substitute ${executable} $out/libexec/pantheon --subst-var out
-    substitute ${executable-wayland} $out/libexec/pantheon-wayland --subst-var out
-    chmod +x $out/libexec/pantheon{,-wayland}
-
     # absolute path patched sessions
     substitute ${xsession} $out/share/xsessions/pantheon.desktop --subst-var out
     substitute ${wayland-session} $out/share/wayland-sessions/pantheon-wayland.desktop --subst-var out