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devel0, thanks for the logs. Unfortunately the graphics corruption is not reproducible here: Ubuntu 18.04.3, Mesa 19.0.8, AMD GPU.

devel0, I saw a similar graphics issue with Ubuntu 19.10 host. This is fixed in 6.0.x revision 135060 https://www.virtualbox.org/wiki/Testbuilds Please test if this build also helps in your case.

Now it work as expected with VirtualBox 6.0.6, of course the performance is lower than the host (33fps vs 60fps) but there are no trouble of random rectangle regions and that is a huge improvement in my opinion.
HOST: fps 60 - gpu usage 90% - gpu mem usage 20%
GUEST: fps 33 - gpu usage 70% - gpu mem usage 23%

sunlover wrote:devel0, I saw a similar graphics issue with Ubuntu 19.10 host. This is fixed in 6.0.x revision 135060 https://www.virtualbox.org/wiki/Testbuilds Please test if this build also helps in your case.

the problem of the menu without background (it's transparent) back again if upgrade win10 to latest version,
previously with 10.0.18362 3d works

now after upgrade to 10.0.19041 with 3d enabled I got the transparency problem of the window main menu like in previous issues.
vbox log attached