Add missing usings

Author: AristurtleDev

articles/tutorials/building_2d_games/20_implementing_ui_with_gum/index.md

@@ -502,7 +502,7 @@ Now that we have setup the UI for the title scene, we will add a pause menu to o
 
 First, open the *GameScene.cs* file in the game project and add the following using declarations to the top of the `GameScene` class.
 
-[!code-csharp[](./snippets/gamescene/usings.cs?highlight=2,7-9)]
+[!code-csharp[](./snippets/gamescene/usings.cs?highlight=2-3,8-10)]
 
 Next, add the following fields:
 

articles/tutorials/building_2d_games/20_implementing_ui_with_gum/snippets/gamescene/usings.cs

@@ -1,4 +1,5 @@
 using System;
+using Gum.DataTypes;
 using Gum.Wireframe;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Audio;