Bug 434176 - Task Manager set to show per-desktop or per-screen tasks does not update after screen setup change
Summary: Task Manager set to show per-desktop or per-screen tasks does not update afte...
Alias: None
Product: plasmashell
Classification: Plasma
Component: Task Manager and Icons-Only Task Manager (show other bugs)
Version: 5.19.5
Platform: Ubuntu Linux
: NOR normal
Target Milestone: 1.0
Assignee: Eike Hein
Keywords: multiscreen
: 452110 452973 (view as bug list)
Depends on:
Reported: 2021-03-09 08:30 UTC by Kay-Michael Voit
Modified: 2024-02-08 17:58 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed In: 6.0


Note You need to log in before you can comment on or make changes to this bug.
Description Kay-Michael Voit 2021-03-09 08:30:57 UTC
I have a 3-screen setup consisting of one notebook (left) and 2 external screens (center, right). Each screen has a panel with a task manager that only shows the tasks from the specific screen, desktop and activity.
When I close the notebook, the respective screen is deactivated and the windows are moved to the center screen, but are not shown in the Task Manager. 
When I open the notebook up again, windows are moved back, and are shown in the left screens task manager, however, the center screen task manager is now *empty*, not even showing the center screen tasks.
This can be fixed by moving the panel to the right screen and back.

In a 3-screen setup:
1. Create Task Managers on each screen, only showing that screens/desktops/activities tasks.
2. Start tasks on all three screens.
3. Deactivate left screen (e.g. close notebook).
4. Activate left screen.
5. Move center screens task bar to right screen and back.


After step 3, the windows from the deactivated left screen will show up on the center screen, but are not represented in the center Task Manager.

After step 4, the windows are back on the left screen, but the center Task Manager is empty.

After step 5, everything is back to normal again.

Task Manager should reflect the tasks on the respective screens all the time.

Linux/KDE Plasma: Ubuntu 20.10
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.14.2

This has been going on for a few Ubuntu versions now, it does not seem to be 20.10 specific.
Comment 1 Kay-Michael Voit 2021-03-17 09:13:59 UTC
This also occurs when I detach my notebook from the docking station, effectively reducing the screens to one. Task manager is empty now and I have to switch applications with Alt+Tab. Since I cannot move the panel to another screen, I currently do not know any workaround fix for this.
Comment 2 Nate Graham 2022-04-25 17:11:35 UTC
*** Bug 452110 has been marked as a duplicate of this bug. ***
Comment 3 Nate Graham 2022-04-25 17:11:40 UTC
*** Bug 452973 has been marked as a duplicate of this bug. ***
Comment 4 Nate Graham 2024-02-08 17:58:19 UTC
This is fixed in Plasma 6!