anchor.diff:  
     do base.VSync <- VSyncMode.On
   
  -  let positionData = [|Vector3(-1.0f, -1.0f,  1.0f);
  -                      Vector3( 1.0f, -1.0f,  1.0f);
  -                      Vector3( 1.0f,  1.0f,  1.0f);
  -                      Vector3(-1.0f,  1.0f,  1.0f);
  -                      Vector3(-1.0f, -1.0f, -1.0f);
  -                      Vector3( 1.0f, -1.0f, -1.0f);
  -                      Vector3( 1.0f,  1.0f, -1.0f);
  -                      Vector3(-1.0f,  1.0f, -1.0f)|]
  +  let positionData = [|Vector3(-0.7f, -0.7f,  0.7f);
  +                      Vector3( 0.7f, -0.7f,  0.7f);
  +                      Vector3( 0.7f,  0.7f,  0.7f);
  +                      Vector3(-0.7f,  0.7f,  0.7f);
  +                      Vector3(-0.7f, -0.7f, -0.7f);
  +                      Vector3( 0.7f, -0.7f, -0.7f);
  +                      Vector3( 0.7f,  0.7f, -0.7f);
  +                      Vector3(-0.7f,  0.7f, -0.7f)|]
     let indicesData = [|
                        // front face
  -                     0; 1; 2; 2; 3; 0;
  +                     0; 3; 2; 1;
                        // top face
  -                     3; 2; 6; 6; 7; 3;
  +                     3; 2; 6; 7;
                        // back face
  -                     7; 6; 5; 5; 4; 7;
  +                     7; 6; 5; 4;
                        // left face
  -                     4; 0; 3; 3; 7; 4;
  +                     4; 0; 3; 7;
                        // bottom face
  -                     0; 1; 5; 5; 4; 0;
  +                     4; 5; 1; 0;
                        // right face
  -                     1; 5; 6; 6; 2; 1; |]
  +                     1; 5; 6; 2; |]
     let normalData = [| Vector3(-1.0f, -1.0f,  1.0f);
                       Vector3( 1.0f, -1.0f,  1.0f);
                       Vector3( 1.0f,  1.0f,  1.0f);
  
positive.code:   override o.OnUnload(e) =
      GL.BindBuffer(BufferTarget.ArrayBuffer, 0)
      GL.DeleteBuffer(vbo)
      GL.DeleteBuffer(indices)
  
      GL.UseProgram(0)
  
negative.code:     GL.Clear(ClearBufferMask.ColorBufferBit ||| ClearBufferMask.DepthBufferBit)
  
      time <- time + (float32)e.Time;
      let mutable lookat = Matrix4.RotateX(time) * Matrix4.RotateY(time) * Matrix4.LookAt(Vector3(0.0f, 0.0f, -4.0f), Vector3.Zero, Vector3.UnitY)
      GL.UniformMatrix4(modelViewLocation, false, &lookat)
  
      GL.DrawElements(BeginMode.Quads, indicesData.Length, DrawElementsType.UnsignedInt, 0)
  
      GL.Flush()
      base.SwapBuffers()
  