diff --git a/agsbox2d_demo/room4.asc b/agsbox2d_demo/room4.asc
index 7b32bf5..e670b06 100644
--- a/agsbox2d_demo/room4.asc
+++ b/agsbox2d_demo/room4.asc
@@ -17,6 +17,7 @@ Physical box3;
 Physical box4;
 
 Physical ball2;
+Physical ball3;
 
 Body*[] setWalls(World* wrld) { 
   Body* _w[]; 
@@ -95,6 +96,16 @@ function room_Load()
     ball2.shape = AgsBox2D.CreateCircleShape(12.0);
     ball2.fixture = AgsBox2D.CreateFixture(ball2.body, ball2.shape, 1.0); 
     ball2.fixture.Restitution = 0.5;  
+    ball2.fixture.CategoryBits = 2;
+    ball2.fixture.MaskBits = 65535-4;
+    
+    ball3.body = AgsBox2D.CreateBody(world, 40.0, 30.0, eBodyDynamic);
+    ball3.body.FixedRotation = false;
+    ball3.shape = AgsBox2D.CreateCircleShape(14.0);
+    ball3.fixture = AgsBox2D.CreateFixture(ball3.body, ball3.shape, 2.0); 
+    ball3.fixture.Restitution = 0.7;
+    ball3.fixture.CategoryBits = 4;
+    ball3.fixture.MaskBits = 65535-2;
     
   }
 
diff --git a/agsbox2d_demo/room4.crm b/agsbox2d_demo/room4.crm
index b436eb1..546431a 100644
Binary files a/agsbox2d_demo/room4.crm and b/agsbox2d_demo/room4.crm differ