VirtualBox OS/2 Guest Additions had been updated to version 7.2.0.
The VirtualBox Changelog does not specify the changes on the OS/2 additions, but on this occasion there had been an improvement for copying files between the guest and host with "Shared Folders".
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.