
I noticed that the OS/2 drivers that are included on Virtualbox Guest Additions were updated at the release of VirtualBox 6.0.6 for other platforms.
The updated files are gengradd.dll, VBoxControl.exe, VBoxGuest.sys, vboxmouse.sys, VBoxReplaceDll.exe, VBoxService.exe and you can see the changelog here.
- OS/2 guests: shared folder fixes (bug #18376 and bug #18379)
If you are running OS/2-ArcaOS-eCS on a Virtualbox VM you can find this files on "Devices - Insert Guest Additions CD Image...", after that check the OS/2 CD drive inside the /OS2 directory.
Parts of the source code of this drivers can be found on the VirtualBox source code repository.