i3: support for workspace_layout option

modules/services/window-managers/i3.nix

@@ -400,6 +400,16 @@ let
         example = "Mod4";
       };
 
+      workspaceLayout = mkOption {
+        type = types.enum [ "default" "stacked" "tabbed" ];
+        default = "default";
+        example = "tabbed";
+        description = ''
+          The mode in which new containers on workspace level will
+          start.
+        '';
+      };
+
       keybindings = mkOption {
         type = types.attrs;
         default = {
@@ -734,6 +744,7 @@ let
     focus_follows_mouse ${if focus.followMouse then "yes" else "no"}
     focus_on_window_activation ${focus.newWindow}
     mouse_warping ${if focus.mouseWarping then "output" else "none"}
+    workspace_layout ${workspaceLayout}
 
     client.focused ${colorSetStr colors.focused}
     client.focused_inactive ${colorSetStr colors.focusedInactive}