Screen Flash when motorcad instantiated

[mhss22]

How do you stop the screen from flashing when you instantiate the pymotorcad class ?
example here

1 self.mcad = pymotorcad.MotorCAD()
2
3 # turn off the UI
4 self.mcad.set_visible(False)
5
6 # Ensure Motor-CAD does not create any dialogs requesting user response
7 self.mcad.set_variable("MessageDisplayState", 2)

i get screen open then close between line 1 and line 4

Thanks
Malcolm