[Bug]: Fullscreen Windows 11 VM on Linux Mint + Compiz jumps from its assigned workspace to the currently active workspace after a few minutes (regression in 7.2.16)

[maxchendt]

Component

GUI

Version

7.2.16

Host OS Type

Linux

Host OS name + version

Linux Mint 22.3 Zena 64-bit
Kernel: Linux 6.8.0-138-generic x86_64
Desktop: MATE 1.26.2
Window manager: Compiz
Workspaces: 4 × 1 (horizontal viewports)

Host Architecture

x86_64

Guest OS Type

Windows

Guest Architecture

x86_64

Guest OS name + version

Windows 11 LTSC

Component

GUI / Full-screen mode / Host window manager integration

What happened?

After upgrading the host from VirtualBox 7.1.16 to 7.2.16, a Windows 11 LTSC VM that is running fullscreen on workspace 2 is periodically moved onto whichever workspace is currently visible.

Typical case:

• win11VM is fullscreen on workspace 2.
• I switch to workspace 3 and browse the web.
• After a few minutes (roughly several minutes, not immediately), the fullscreen VM window appears on workspace 3 by itself.

The VM does not stay on the workspace where it was placed. This did not happen with 7.1.16 on the same host, same Compiz setup, same guest.

This looks like a regression in 7.2 fullscreen handling versus Compiz viewports (Compiz uses one large desktop split into viewports, not separate workspaces like Marco).

How can we reproduce it?

1. Host: Linux Mint 22.3, MATE, Compiz, 4×1 workspaces.
2. Install VirtualBox 7.1.16. Start a Windows 11 guest in fullscreen on workspace 2. Switch to another workspace and leave it for several minutes. The VM stays on workspace 2.
3. Upgrade host VirtualBox to 7.2.16 (matching Extension Pack). Keep the same VM, same Guest Additions as far as the upgrade path goes.
4. Put the VM fullscreen on workspace 2 again. Switch to workspace 3 and use the host (e.g. a browser) for a few minutes.
5. Observe the fullscreen VM window jump onto workspace 3.

Expected behavior

Same as 7.1.16: the fullscreen VM remains on the workspace / Compiz viewport where it was started (workspace 2). Switching the host to another workspace must not relocate the VM window.

Actual behavior

After a few minutes the fullscreen VM is moved to the currently active workspace.

Things already tried (did not restore 7.1 behavior)

• VBoxManage setextradata global GUI/Fullscreen/LegacyMode true then restart VirtualBox Manager and the VM.
• Compiz: Place Windows → fixed viewport for the VM window.
• Compiz Workarounds / focus-prevention tweaks.
• Reinstalling Guest Additions for 7.2.16.

Workaround that avoids the bug: stay on VirtualBox 7.1.x (confirmed working on 7.1.16).

Additional notes

• The guest is not being “switched” from inside Windows; the host Compiz viewport of the VirtualBox fullscreen window changes.
• Timing (minutes, not instant) suggests a periodic guest/host event (Guest Additions, clipboard, mouse integration, display mode refresh, urgency/attention hint) interacting with the new 7.2 fullscreen path.
• Compiz + VirtualBox fullscreen has historically needed GUI/Fullscreen/LegacyMode; that extra data did not fix it on 7.2.16.