How to force OpenGL2 (SetForceGL2(bool))?

I want force OpenGL 2.
in documentation

void SetForceGL2 (bool enable)
Set forced use of OpenGL 2 even if OpenGL 3 is available. Must be called before setting the screen mode for the first time. Default false. No effect on Direct3D9 & 11.

If I call SetForceGL2 inside setup before screen mode (as I guess it is here), program crash.
if I use
GetSubsystem<Graphics>()->SetForceGL2(true); inside void Start() function. (If I add it in setup() or initial class function MyApp(){}, it compile without problem but after run program it crash.)
Program don’t crash, but I am not sure if OpenGL 2 is set up.
It is right what I am doing?

If you’re using Engine (which I recommend, as it’s a pain to do everything that Engine does yourself, and with no real benefit) then you don’t need to call SetForceGL2() explicitly. Just pass the flag into Engine::Initialize as one of the parameters. Engine::Initialize will call it at the proper time if needed.

Thanks, but to be sure I do it correctly
I add inside

virtual void Setup()
	engineParameters_[EP_FORCE_GL2] = true;

it is right?

Yes, that seems correct. Any luck?