Bug 515297

STEPS TO REPRODUCE:

Start a Plasma session on X11 inside a VirtualBox VM (3D Acceleration DISABLED).

Open multiple windows of the same application (e.g., Konsole or Dolphin) to trigger grouping in the Task Manager.

Click on the grouped icon to open the window selection popup.

Repeat if it doesn't happen the first time.

OBSERVED RESULT: The entire plasmashell process freezes. The mouse cursor remains movable and other windows stay interactive, but the panel/taskbar is completely unresponsive.

FREQUENCY: The issue is intermittent but occurs very frequently (highly reproducible). It doesn't happen 100% of the time, but it happens often enough to make the desktop nearly unusable without frequent restarts of the shell.

EXPECTED RESULT: The window selection popup should appear smoothly every time without freezing the shell.

REGRESSION INFORMATION: This issue started appearing approximately one week ago, following the latest updates. It was working correctly before the transition to the current versions of Plasma, Frameworks, and Qt. It feels like a race condition in the Task Group Dialog rendering on X11 under software rendering (llvmpipe).

ENVIRONMENT / VERSIONS:

Virtualization: VirtualBox [7.2.4] (No 3D Acceleration)

Guest OS: KDE neon (User Edition)

Graphics Platform: X11

KDE Plasma Version: 6.5.5

KDE Frameworks Version: 6.22.0

Qt Version: 6.10.1

ADDITIONAL NOTES:

I have already tried disabling "Thumbnails" in the Task Manager settings, but the freeze persists.
Since I am using a VM without 3D acceleration, the system is using software rasterization.