In the task manager settings, I've checked : - Only show tasks from the current screen - Only show tasks from the current desktop - Only show tasks from the current activity As my computer is a laptop, the second screen is not always plugged in. I suspend the computer instead of shutting it down. This bug is not easily reproductible. It happens approximatly once or twice a week. If I instanciate an new default panel on the main screen, it works without the bug. This bug is maybe linked to the 372805 (https://bugs.kde.org/show_bug.cgi?id=372805) as the animation when I minimize a window on the 2nd screen reduce it on the main screen.
My configuration : - Debian 9 (stable) - KDE Plasma 5.8.6 - KDE Frameworks 5.28.0 - Kernel 4.9.0-4-amd64
I can confirm this bug on my system. I have a laptop with an external monitor and one task manager on each screen set to show just the windows from that screen. I get the following two erroneous behaviors: 1) When unplugging the external monitor, the laptop screen task manager sometimes shows just the windows from the no-longer-available external screen. 2) When plugging in the external monitor, sometimes both task managers will choose to display the window list from just one of the screens. So far I have 100% success with the following workaround (that has to be done each time the problem occurs) -- a) remove the problematic task manager from the panel b) add a new task manager to the panel. So it would seem that if the task manager would just query which screen it is on, it would get the right answer, with the problem being that it just fails to do so. Plasma 5.13.5 Frameworks: 5.50.0 Qt 5.11.1
I just discovered another failure mode: 3) Sometimes a task manager set to only display tasks from the current screen displays no tasks at all. If I remove the filter, then all tasks are shown, as expected. To further add detail, unchecking the "show only tasks from the current screen" box, applying the changes, and then checking it again does not fix any of these errors. Neither does removing the task manager and then undoing that action. Only removing the task manager and then adding a new one will temporarily work around the issue.
*** This bug has been marked as a duplicate of bug 414743 ***