Issue with spice guest resizing on windows

I’m trying to understand a (probably silly) issue I’m having with a VM under Windows; related to spice // spice guest // resizing.

Here is the context:
I have setup a VM win Windows 10 (and one with Windows 11), in both incus and libvirt.
I have followed (reasonably closely…) the instructions as in How to run a Windows virtual machine on Incus on Linux (as referenced in one of the posts here)
Basically:

  • The end goal is to have guest resizing working (no… actually: note to self: the objective was to have a Windows 11 VM… guest resizing is just something I got lost into while trying…)
  • I have create 2 VMs based on the insturciotns above (creates a small script to allow creating a VM by just providing the name and the installation image)
  • Windows installed with an unattended file (file created here
  • On all 4 (2 Win11; 2 Win10) I have then installed the virtio Windows guest tools (file: virtio-win-guest-tools.exe - as instructed in the list above)
  • I also have another VM, from images coming from linuxcontainers, with ubuntu (23.10 I believe)

I would say that I obtain consistently the same behaviour:

  • If I try to resize the guest window from virt-manager; it works
  • If I try to resize the guest window from incus, it doesn’t
  • If I try to resize ubuntu guest (in incus), it works

I think I have tried all (logical) combinations I could think of, without success:

  • QXL Driver from RedHat correctly installed
  • Copy-paste works (If I understand correctly, copy-paste relies on guest tools as much as resizing?)
  • Checked teh logs vdagent.log/vdservice.log within guest: I don’t receive events when I resize on Incus, I do recive when I resize in libvirt (and: if I copy-paste I receive events in either one of these files)
  • I have checked for missing drivers… in incus, I have 3 missing drivers. But if I’m not wrong, these are: 2 PIC deviced for Plan9 (Device ID 1049); and one for VirtFS (Device ID 1053)
  • I have tried to check (visually…) if the devices created from libvirt and incus are the same: they seem to be /fairly/ the same (there are differences… But not related to spicevmc device)
  • In a desperate attempt, I have replaced the binary of qemu-system-X86_64 within /opt/incus/bin (which is V9.2) with the system one (/usr/bin/qemu-system_X86_64 – version 8.2). No difference.
  • I have tried to open the spice interface of the libvirt instance directly from remove-viewer (because in libvirt you actually use another binary, which is called virt-viewer): no difference (resizing still works)
  • I have tried to manually resize (increase resolution of display) within Windows: works
  • IU have tried spicy: same behaviour…

I would say I’m now out of options: I don’t know know what else to try / where to look more than that.

I admit this is a silly thing… I don’t need resizing that hard… But still, it was nice to have, and I have no explanation as why it fails.