Small screen on vbox on MacBOok

In order to practice and learn G commands I want to run Linux CNC inside
Virtual box 6.1 on a MacBook running Big Sur 11.2.1.

I installed Virtual Box. Practiced by setting up a Debian guest. No problems.
Downloaded "linuxcnc-2.8.0-buster.iso". Created another VM using that ISO. No problems. VM starts and looks good.

I can runLinuxCNC. All looks beautiful, except,
the window in the vbox guest does not seem to re-size when I pause the cursor over a corner, wait for an arrow to appear, and then move the cursor to increase size. Yes, the window gets bigger. But, LinuxCNC app is still the same size. The only change is the border gets bigger.

Alas, the area inside Linux CNC is only one line high!. Too small to do any learning.

I suspect this is a Mac, or vbox issue, and not a linuxcnc issue, but I figured somebody else my have solved it. I searched the forums but found nothing.

Any suggestions?

Thanks.

Thats from my helpfile to get fullscreen in Virtualbox / Debian Buster

Debian 10 Buster LinuxCNC in VirtualBox Vollbild

Did you install the guest additions?

I use VMWare Fusion on a iMac without issues, I did find VBox a bit "laggy" in the graphics department.

Did you fix this. Same issue on Windows

Hi. I am having the same issue on windows. cna you give me more context?

What do you mean by typing: /etc/default/grub
comment:
#GRUB_CMDLINE_LINUX="initrd=/install/gtk/initrd.gz"

then when you tybe $uname -r
my linux name being "CNC" am i supposed to type

sudo apt install linux-headers-cnc -r
or something else?