i3: add notification option to startup submodule

Fixes https://github.com/rycee/home-manager/issues/129.

modules/misc/news.nix

@@ -448,6 +448,20 @@ in
           A new program module is available: 'programs.neovim'.
         '';
       }
+      {
+        time = "2017-11-14T19:56:49+00:00";
+        condition = with config.xsession.windowManager; (
+          i3.enable && i3.config != null && i3.config.startup != []
+        );
+        message = ''
+          A new 'notification' option was added to
+          xsession.windowManager.i3.startup submodule.
+
+          Startup commands are now executed with the startup-notification
+          support enabled by default. Please, set 'notification' to false
+          where --no-startup-id option is necessary.
+        '';
+      }
     ];
   };
 }

modules/services/window-managers/i3.nix

@@ -20,6 +20,15 @@ let
         description = "Whether to run command on each i3 restart.";
       };
 
+      notification = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          Whether to enable startup-notification support for the command.
+          See <option>--no-startup-id</option> option description in the i3 user guide.
+        '';
+      };
+
       workspace = mkOption {
         type = types.nullOr types.string;
         default = null;
@@ -388,8 +397,8 @@ let
         '';
         example = literalExample ''
           [
-            { command = "systemctl --user restart polybar"; always = true; }
+            { command = "systemctl --user restart polybar"; always = true; notification = false; }
-            { command = "dropbox start"; }
+            { command = "dropbox start"; notification = false; }
             { command = "firefox"; workspace = "1: web"; }
           ];
         '';
@@ -479,8 +488,10 @@ let
 
   floatingCriteriaStr = criteria: "for_window ${criteriaStr criteria} floating enable";
 
-  startupEntryStr = { command, always, workspace, ... }: ''
+  startupEntryStr = { command, always, notification, workspace, ... }: ''
-    ${if always then "exec_always" else "exec"} --no-startup-id ${
+    ${if always then "exec_always" else "exec"} ${
+      if (notification && workspace == null) then "" else "--no-startup-id"
+    } ${
       if (workspace == null) then
         command
       else