Today I learned how to enable the full screen mode for VMs in #QubesOS. It is surprisingly easy.
Especially since i thought it was impossible. Well, now I can watch stuff in full screen on my Laptop again, I guess that is a win.

You just have to open a Terminal in Dom0, and enter:

sudo nano /etc/qubes/guid.conf

That will open the nano text editor. There you will have to scroll down to:

# most of setting can be set per-VM basis

VM {
};

Now you add the following lines after "VM{" :

Your_VM_Name: {
allow_fullscreen = true;
};

Than you restart the VM and watch your movies in full Screen.

Just make sure you have really left the full screen mode before you enter any sensitive information afterwards.

https://www.qubes-os.org/doc/full-screen-mode/