Hi Steve,
Thanks for the modification. Our systems must work differently because _SCREEN HIDE, _SCREENSHOW did fix the screen artifact problem for me, the screen just blinks and then you see the bug(s). Your mod leaves a shadow screen, if I run it from the QB64 IDE and it seems a 50/50 change for artifact from the .exe, here are what I am seeing in screen shots attached. BTW the MS Windows button let's me access tools when I have Full Screen App running eg, for screen shots.
So if my code leaves screen artifacts or screen shadows then try Steve's mod or vice versa :)