Posted by Roland Schützig on Sep 19, 2021; 11:56am
URL: https://forum.jogamp.org/ScreenScaling-ignored-tp4041281p4041291.html

That solved the issue with the ingnored screenScaling indeed. Thanks a lot.
I got https://jogamp.org/deployment/v2.4.0-rc-20210111/archive/jogamp-fat-all.7z and the problem is gone (with using version 1.6.2 of java3D as you suggested, of course).

Now I have this "An illegal reflective access operation has occurred" warning.
After some searching I ended up with using JDK 12 and Java3D 1.7.0 but the warning was still there:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.jogamp.java3d.JoglPipeline$1 (file:/C:/tools/Java3D/java3D_170/j3dcore.jar) to method sun.awt.Win32GraphicsDevice.getScreen()
WARNING: Please consider reporting this to the maintainers of org.jogamp.java3d.JoglPipeline$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

And finally - following the advise giving in the post https://forum.jogamp.org/Java3D-Illegal-reflective-access-td4040908.html by user "goodwilling" - the message goes away with the Java VM option:
--add-exports=java.desktop/sun.awt=ALL-UNNAMED

I just don't know, if it is clever to hide the messages and some future JDK release is not benign anymore and makes it an error instead a mere warning.