I have a BenQ monitor connected to my Dell Latitude E7440 via HDMI. I upgraded to Kubuntu 16.04 recently. Since then, whenever I change my monitor setup, the primary output is not activated properly (the task bar does not show up on the selected output). I haven't found out a way to reproduce this properly, but it happens basically everytime. Sometimes I have to reboot, to get a working screen again. Reproducible: Always Steps to Reproduce: 1. Connect a monitor to the HDMI port 2. Open KScreen 3. Setup dual screen (laptop's monitor → primary output, HDMI → secondary output) 4. Hit "Apply" button (flickering appears) 5. Switch primary output to HDMI 6. Hit "Apply" button (flickering appears) Actual Results: Task bar stays on laptop's monitor. Expected Results: Task bar shows up on external monitor, which is connected to the HDMI port without any flickering. The flickering loos as if the system is trying to figure out what to do :D Sorry, it is very hard for me to provide you with proper input. Let me know if I can do anything to give you more information.
# Packages kde-config-screenlocker 5.5.5-0ubuntu1 amd64 kscreen 4:5.5.5-0ubuntu1 amd64 libkscreenlocker5:amd64 5.5.5-0ubuntu1 amd64 libxcb-randr0:amd64 1.11.1-1ubuntu1 amd64 libxrandr2:amd64 2:1.5.0-1 # System Kubuntu 16.04 Kernel 4.4.0-21-generic #37-Ubuntu SMP x86_64
moving to plasmashell. It's plasmashell's task to react on primary screen changes.
Also, we fixed this issue with Plasma 5.8, please test that. (You can use Neon git/unstable for example.) If the issue persists, please reopen this bugreport. Thanks!