FBSD X11 guest in VBox: mouse pointer caught in guest forever

Hello,

I'm running FreeBSD 13.1-RELEASE-p1 in a governmental appliance based upon Linux and VBox
4.1.26. I have to mention that fact because there is not much option to configure the VBox.

After a crash of the base system damaging the FBSD ZFS based guest beyond repair I had to
reinstall X11 and have to configure it from memory, because this part is not backup'd.

FreeBSD 13.1-p1 and X11 (xdm, windowmaker) is up and running, everything is fine, I got a
mouse pointer, the keyboard with German layout is well supported. 

emulators/virtualbox-ose-guest-additions is installed as instructed in the handbook.

The target computer is a Lenovo T590 with a remote/cordless mouse (if this information is of
any use).

Problem: once clicking the mouse to enter login data on xdm, the mousepointer is caught
forever within the guest. Usually the combination "left-Ctrl right-Ctrl" should release the
mouse pointer to reach the Vbox. This is not working anymore.

Somehow I have the strange feeling that the keyboard setup is missing something so the correct
keys are not mapped according the physical layout, but there is no hint  what
XkbModel/XkbVariant I should use (tried pc105, thinkpad or avoid the Option, with no effect so
far).

Any ideas?

Kind regards

O. Hartmann

-- 
O. Hartmann