gnome3.gnome-terminal-server: init module

since gnome3.22 gnome-terminal uses a systemd service for it's backend
server.

nixos/modules/module-list.nix

@@ -166,6 +166,7 @@
   ./services/desktops/gnome3/gnome-keyring.nix
   ./services/desktops/gnome3/gnome-online-accounts.nix
   ./services/desktops/gnome3/gnome-online-miners.nix
+  ./services/desktops/gnome3/gnome-terminal-server.nix
   ./services/desktops/gnome3/gnome-user-share.nix
   ./services/desktops/gnome3/gvfs.nix
   ./services/desktops/gnome3/seahorse.nix

nixos/modules/services/desktops/gnome3/gnome-terminal-server.nix

@@ -0,0 +1,44 @@
+# GNOME Documents daemon.
+
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let
+  gnome3 = config.environment.gnome3.packageSet;
+in
+{
+
+  ###### interface
+
+  options = {
+
+    services.gnome3.gnome-terminal-server = {
+
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable GNOME Terminal server service,
+          needed for gnome-terminal.
+        '';
+      };
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf config.services.gnome3.gnome-terminal-server.enable {
+
+    environment.systemPackages = [ gnome3.gnome_terminal ];
+
+    services.dbus.packages = [ gnome3.gnome_terminal ];
+
+    systemd.packages = [ gnome3.gnome_terminal ];
+
+  };
+
+}

nixos/modules/services/x11/desktop-managers/gnome3.nix

@@ -108,6 +108,7 @@ in {
     services.gnome3.gnome-documents.enable = mkDefault true;
     services.gnome3.gnome-keyring.enable = true;
     services.gnome3.gnome-online-accounts.enable = mkDefault true;
+    services.gnome3.gnome-terminal-server.enable = mkDefault true;
     services.gnome3.gnome-user-share.enable = mkDefault true;
     services.gnome3.gvfs.enable = true;
     services.gnome3.seahorse.enable = mkDefault true;