QWT 4.2.2 Severe strobing when starting up / shutting down Win 10

[jmynes]

Qubes OS release

Qubes OS 4.3, Qubes OS 4.2

Brief summary

Booting or shutting down my Windows 10 qube is causing severe, even dizzying flicker

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I have Windows 10 Qubes with QWT 4.2.2 installed, on Qubes OS 4.2.4
I restored them as backups from a fully updated Qubes OS 4.3.0 rc3 system, today

My Framework 16 laptop's dom0 resolution is 1920x1200, 1x scale, @165hz, on a display that supports up to 2560x1600

This reliably occurs only after reducing the resolution to 1920x1080 for my Win10 qubes
This does not occur in my QWT 4.1.69 Win 10 qube, including at 1920x1080

Here is a very short 30fps video demonstrating the issue (epilepsy warning)
https://github.com/user-attachments/assets/5e171c34-9c3a-4b2f-a0bb-6a1149d1b842

This looks much more severely rapid in person, and is sometimes 10+ seconds. My camera made it look like banding, but instead it is much more like a strobe light

Steps to reproduce

1. Install Windows 10 with QWT 4.2.2
2. Set resolution to 1080p
3. Start or shutdown your qube

Expected behavior

Window should not have to redraw (?) this many times

Actual behavior

Flashbanged by a Windows 10 qube

Additional information

No response

[marmarek]

It might be related to GUI agent that is now available on Windows 10 too with new QWT. Old QWT supported only Windows 7 in this regard. You can compare by disabling it during QWT installation.

[Euwiiwueir]

On 4.3, or a patched qubes-gui-daemon on 4.2, the strobe effect could perhaps be mitigated with:

[user@dom0 ~]$ qvm-features <windows qube name> gui-window-background-color black

Assuming it is a redraw loop, not something else.

[jmynes]

Hmm, appreciated, but unfortunately this did not resolve the issue.