I've seen something like this through GPxPatch panels (GPxCInfo tab) => Fx help. Help items F1 through F9.
I don't remember now, but it must be some TV Style F1
Maybe 2018.....
Link: [
www.grandprixgames.org]
So you must configure this ( turn on ) and then through the X and Y coordinates show the F1, F2......
I believe you can put a label or an image.....
Evandro ( Brazil )