anchor.diff:          let vertexSize = sizeof<single> * 2
           let vertexDataSize = vertexSize * 4
           let vertexDataPtr = GCHandle.Alloc (vertexData, GCHandleType.Pinned)
  -        try OpenGL.Gl.BufferData (OpenGL.BufferTarget.ArrayBuffer, uint vertexDataSize, vertexDataPtr.AddrOfPinnedObject(), OpenGL.BufferUsage.StaticDraw)
  +        try OpenGL.Gl.BufferData (OpenGL.BufferTarget.ArrayBuffer, uint vertexDataSize, vertexDataPtr.AddrOfPinnedObject (), OpenGL.BufferUsage.StaticDraw)
           finally vertexDataPtr.Free ()
           Assert ()
   
  
positive.code:         OpenGL.Gl.BindBuffer (OpenGL.BufferTarget.ElementArrayBuffer, indexBuffer)
          let indexDataSize = uint (indexData.Length * sizeof<uint>)
          let indexDataPtr = GCHandle.Alloc (indexData, GCHandleType.Pinned)
          try OpenGL.Gl.BufferData (OpenGL.BufferTarget.ElementArrayBuffer, indexDataSize, indexDataPtr.AddrOfPinnedObject(), OpenGL.BufferUsage.StaticDraw)
          finally indexDataPtr.Free ()
          Assert ()
  
  
negative.code:           LightPositionsUniform : int
            LightColorsUniform : int
            PhysicallyBasedShader : uint }
  
      type [<StructuralEquality; NoComparison>] PhysicallyBasedSurface =
          { VertexBuffer : uint
            NormalBuffer : uint
            TexCoordsBuffer : uint
            IndexBuffer : uint }
  
      /// Assert a lack of Gl error. Has an generic parameter to enable value pass-through.
      let Assert (a : 'a) =
  