OpenGL and NSScreen.mainScreen.backingScaleFactor

[Key-Real]

I init openGL

now i wanna set

Code: Pascal  [Select][+][-]

1. glPixelZoom(pixelSizeX, -pixelSizeY);

to dispaly a image with width and height to the entire window

for this I do:

Code: Pascal  [Select][+][-]

1.     rect:= window.frame;
2.     WindowBackingRect :=  window.convertRectToBacking(rect);
3.  
4.   pixelSizeX :=  WindowBackingRect.size.width / width / NSScreen.mainScreen.backingScaleFactor;
5.   pixelSizeY :=  WindowBackingRect.size.height / height / NSScreen.mainScreen.backingScaleFactor;
6.  

under High Sierra 10.13.6 on an intel mac from 2011 NSScreen.mainScreen.backingScaleFactor return 1 because there is no retina.
under Sonoma 14.3 an an intel mac from 2020 NSScreen.mainScreen.backingScaleFactor return 2 because of retina.
this works correct.

under Venture 13.6 on an aarch64 mac from 2020 NSScreen.mainScreen.backingScaleFactor returns 2 BUT the image is only half so big as it should be.

(if i let the scale factor away on the new intel mac, the image is twice big as it should be. On the new AArch64 mac it is correct.)

what to do?