Problem with play in full screen on internal display
I have problem with play games in fullscreen on internal display. When I start game in window mode and switch from fake monitor to my internal desktop every thing is ok. But when I try switch to full screen or full screen windowed mode my game going back to fake display.
I am pretty sure that the behavior described here is normal, unfortunately…
The so-called window-drag or fake-display method does allow you to play games in windowed mode on the internal screen but not in fullscreen mode.
There is a trick which consists of simulating fullscreen by using borderless windowed mode, but you may have to count with some performance hit doing so. The window-drag method was a lot used 2-3 years ago when eGPU-solutions for gaming on the internal screen of laptops with dGPUs were almost inexistant. Today, there are different solutions which are simply better (for laptops). Now, I don't know about iMacs...
I tested the window-drag method during my journey in this eGPU world some months ago. I share my experience in the thread below if you want some additional piece of information.