Buggy Multi-Monitor Support in KDE

English Hardware
1

KDE and multiple monitor support is poor and buggy.

I have 2 extra monitors attached to a laptop. The third monitor I have in portrait view.
The laptop is attached a docking station, and the monitors are plugged into it with DisplayPort.

Laptop monitor: 1920x1080
Phillips 345B1C: 3440x1440
HP E242: 1200x1920

The Phillips monitor is set as the default main monitor, when the laptop is attached the docking station.**

With OpenSUSE Leap 15.2:**
All my monitors worked fine. Every day when I put my laptop in my docking station at work, both the extra monitors where activated and worked.

Though the Phillips Ultra Wide monitor, I had to turn it off/on, otherwise there could be a chance it didn’t activate.

When ever I had a meeting, I disconnected my laptop from the docking station. Then connected to our meeting room monitor (80" 4K). KDE could never activate this monitor. Though it recognized the monitor, but every time I enabled it, it got disabled.
It only connected to the meeting room monitor, after I rebooted the laptop.

Then I got back to my docking station, and it managed to connect to all my external monitors. It remembered the setup on the docking station.
I though KDE should be able to remember more than one monitor configuration, but does not look like it.

I thought it had to be better upgrading to OpenSUSE Leap 15.3
Alas it got worse.

With OpenSUSE Leap 15.3:
The HP external monitor always become active, but now the Phillips Ultra Wide monitor never comes on when I place my laptop in the docking station. In KDE monitor settings, the Phillips monitor is there, and I can enable it, but when I do, it automatically disables it, cannot connect to it.

Now with Leap 15.3, I have to reboot my laptop every day when I come back to the office.

Maybe what I need is a fresh install, but I am reluctant. It is a big job to reinstall my work laptop, and setup everything again I need to work.

2

Try to disable KScreen 2: https://forums.opensuse.org/showthread.php/563367-Nvidia-and-modesettings-second-display-problem

3

Thanks for the suggestion.

Why would disabling “KScreen 2” fix the issue? I could not see why on the other page.

I forgot to mention. I only have Intel graphics on the laptop, and no NVIDIA/AMD dedicated graphics.

4

Because of “Buggy Multi-Monitor Support in KDE”.

KScreen is the screen management software for KDE Plasma Workspaces

5

That is not a good explanation why I should disable KScreen2.

If I disable this, I would not be able to configure screens in KDE anymore?

If it is so much problem with it, what good is it for.

I just want my computer to discover new screens when attached, and activate them without rebooting.
I also want it to remember my configurations, so when I get back to my docking station, it just works.

6

When I am using KDE even from way back til now, kscreen2 is always disabled as part of my set up.
I never had a problem running 3 monitors with it. Maybe because I am using nvidia. We can ask the two posters
of this thread if running a different video card outside nvidia, if disabling kscree2 is possible, if yes then the advice of those
posters are legitimate. Just my 2 cents.

7

To get more create KDE bug report:

https://en.opensuse.org/openSUSE:Bugreport_KDE
https://community.kde.org/Get_Involved/Issue_Reporting
https://community.kde.org/Bugsquad/Quick_Introduction_to_Bugzilla

https://bugs.kde.org/

8

I disabled KScreen2, but there was one drawback by doing so.
When I detached my laptop from the docking station, all windows was outside of the laptop monitor view.

Usually when KScreen2 is running, all windows is automatically “moved” over to the laptop monitor.
One drawback with that is when I attach my laptop again to the docking station, I have to manually move all these windows back into the external monitors.

This is a feature I still want. When I use my laptop without any monitors attached I was access to all my windows.
So disabling KSCreen2 does not seem like an option for me.

9

With KScreen2 disabled, use arandr to create and save one-line xrandr scripts for your different environments. When switching environments, run the appropriate script. As an alternative to arandr, you can make your own xrandr scripts from scratch using the output names found via inxi -Ga or grep onnect /var/log/Xorg.0.log. A third way xrandr --listproviders sometimes works.

10

I don’t want any halv-automatic scripts in order to get monitors connected.
When I plug in a monitor I want it to just activate and display.

Each day when I plug my laptop into the docking station, only one of the two external monitors comes active.

Laptop monitor: 1920x1080 (60Hz/120Hz)
Phillips 345B1C: 3440x1440 (60Hz/100Hz)
HP E242: 1200x1920 (60Hz)

The laptop monitor is then the Primary monitor.
When plugged into the docking station, I must open settings to enable the missing monitor.
Select the missing monitor
Click Enable
Click Primary
Select 60Hz refresh rate
Click Apply

What good is Save display properties (For any display arrangement) if it cannot do that.

It is tedious that I have to do this at start of every day.

https://i.imgur.com/u4W7Ul7.png

https://i.imgur.com/wQH4bVP.pnghttps://imgur.com/u4W7Ul7https://imgur.com/u4W7Ul7

11

Hi,
I am on xfce but due to almost same problem as yours. I tried mutter but I encountered the same problem
with xfwm4. So I used kwin as my windowmanager and it’s the one that is consistently reading my multi monitor
arrangement that I want it to be. When I saw your attached image I opened the kde-system-settings which was
installed when I installed kwin and when I look at the display config it is save as.

For only this specific display arrangement

Which is not like how you saved yours.
Could this make any difference?

12

–Lets see. I have a little bit unusual hw-setup. A AMD apu and a discrete AMD R7 Gpu. 3 monitors. For me it was working much better to change the order of monitors between internal GPU and discrete GPU.

15.4 is way better then 15.3.

Not even win7 or win10 solve by my experience with laptops and docking/external monitors and your problems. --Reboot.

My what ever opinion.
Regards

13

I’m going to try Save “For only this specific display arrangement”, and see if that solves the problem.

I wanted the settings to save for other configurations also, when I am home office I have an QHD 27" additional monitor.
When I’m at work and in meeting room I want it to recognize the meeting room monitor and automatically connect to it.