Fix "The type 'Label' does not define the field, constructor or member

Fix "The type 'Label' does not define the field, constructor or member
'TextColor'" by removing .TextColor as it is not used.

FSharpExample/Program.fs

@@ -457,7 +457,6 @@ type Demo() = class end
         ml <- new Label(new Rect(3, 17, 47, 1), ustr "Mouse: ")
         Application.RootMouseEvent <- Action<MouseEvent> (
                 fun (me : MouseEvent) ->
-                    ml.TextColor <- Colors.TopLevel.Normal
                     ml.Text <- ustr (
                          (((sprintf "Mouse: (%O,%O) - %O %O" me.X) me.Y) me.Flags) (
                             count <- count + 1