I've just installed Plasma5 on the latest Slackware. I can see all 4 of my monitors. KDE > System Settings > Display Configurations shows the default arrangement as follows:

[AOC 2060W 1600x1900, HDMI-1] [Teleliason IncVOX L19RCTN 1366x768, VGA-1] [HP LV1911 1366x768, HDMI-2] [Auria EQ166L 1366x768, VGA-2]

Using the 'Display Configuration' tool I've rearranged these to reflect my actual physical layout which is:

[Auria EQ166L 1366x768, VGA-2]
[Teleliason IncVOX L19RCTN 1366x768, VGA-1] [AOC 2060W 1600x1900, HDMI-1] [HP LV1911 1366x768, HDMI-2]

That is, with the AOC in the middle and the Auria sitting above the AOC. This works, sort of. I can drag windows among all 4 monitors. The problem is that the upper Auria monitor is shown on the Display Configuration arrangement as partially overlapping the lower AOC monitor, and windows opened on the lower AOC partially show on the upper Auria. I can drag the Auria arrangement position up, but it creates a gap between the upper and lower monitor arrangements. I cannot get the Auria arrangement to rest exactly on top of the AOC -- I either have a gap or an overlap. The problem with the setting having the gap is that when I attempt to drag a window up to the Auria the cursor stops at the top of the AOC monitor and, if I let go of the mouse at that point it makes the window full screen on the AOC. I cannot move my mouse to the Auria monitor at all with the gap arrangement.

Is there a way to fine-tune the position of these windows so that I can have the the upper monitor arrangement touching the lower monitor? No gap, no overlap.

I'd attach an image but I haven't figured out how to make one yet!

Hi!

Depends on which graphics card you use. NVidia with the proprietary driver has the option to exactly enter the values manually using ViewPortIn, ViewPortOut and Panning.
The general way to get there is using a xorg.conf and set fixed positions like described in the ArchlinuxWiki.

If you're on Wayland I only know how to do this in sway, so that would be no help.

koffeinfriedhof, thanks for your comment. I have two NVIDIA GeForce GTX 710 video cards and 4 monitors. I am using the NVIDIA drivers on Plasma4/KDE4. In order to arrange the 4 monitors I need to use NVIDIA's Xinerama program which generates an xorg.conf file. That all worked well for a few years, and kind-of still does, but about a year ago Firefox after 52.9 and LibreOffice after 6.0.2 stopped working properly. For Firefox, any attempt to drag a tab shutdown Firefox. For LibreOffice, the various font/background, etc. drop-down menus stopped working. I've never figured out if the problems resulted from changes the these program, the NVIDIA driver, Xinerama, or the Linux kernel. So, on my Plasma 4 system I'm stuck with these older version of these program. One of the main reasons I want to move to Plasma 5 is to get current on these programs. I have installed the latest NVIDIA driver on the Plasma 5 system, but I have the same problems (e.g. dragging Firefox tabs shuts down Firefox). On both the Plasma 4 and Plasma 5 systems this problem does not occur if not running Xinerama. However, without Xinerama I cannot utilize my 4 montors.

Plasma 5, with the newer KDE, looked to solve all that because it supports 4 monitors natively (Plasma 4, at least with KDE 4) did not. With Plasma 5 I'm almost there except for the problem I posted trying to get the top monitor (Auria EQ166L) positioned correctly. I have found that if I reduce the resolution on that monitor it is better; there is only a minor overlap on the upper and lower screens, but I'd like it to be correctly positioned. I did find ~/.local/share/kscreen/47b...c0d, which contains xorg.conf-like screen positions and geometry which is used by System Settings > Display Configuration to store the configs. For my EQU166L monitor I have:

Code: Select all

    {
        "enabled": true,
        "id": "8538203a52b5c34afef379ad26c84642",
        "metadata": {
            "fullname": "xrandr-EQ166L-000000000000",
            "name": "VGA-1-2"
        },
        "mode": {
            "refresh": 59.7895393371582,
            "size": {
                "height": 768,
                "width": 1366
            }
        },
        "pos": {
            "x": 1478,
            "y": 0
        },
        "primary": false,
        "rotation": 1,
        "scale": 1
    }

This shows the y: position as zero. The problem I find here is that no matter where I move the EQ166L monitor, whether overlapping or gapped, the y coordinate is always zero unless I move the EQ166L monitor to fully inside the outline of the lower monitor (2060W). Then there are different values for y. However, there must be somewhere else KDE stores other coordinates because even though y always = 0 for various placements, when I run 'Display Configuration' it always shows the monitors in the differing configurations to which I moved them.

Ideas?

Plasma4? I thought this is only running in some archaeological museums

So you're using two nvidia cards with two screens attached to every card? Or three/one? Lets try the following (if possible):
- uninstall the proprietary drivers (the system will use nouveau then)
- re/move the xorg.conf (look into xorg.conf.d too) to use the automatic detection system
- create a new, clean user without any configuration files
- Plasma5 login (not a wayland session) with this user, try the monitors overlap without moving them first to test the native layout behaviour. Does it overlap there too?
- After «playing around», set the arrangement as wanted and try again
- To test Wayland you could use sway, but then you must use nouveau.

I don't know the GTX 710 chip, but you can check it using `lspci -nnk | grep -A3 "\[03..\]:" ` and compare the number with this page: https://nouveau.freedesktop.org/FeatureMatrix.html. Dual-head is nearly everywhere supported.

Firefox is not Qt5/KF based, so perhaps you need some gnome-packages to run it smoothly. I don't know which ones as I do neither use slackware nor firefox. You could try to run it using «portal»:
The packages in arch are called xdg-desktop-portal and xdg-desktop-portal-kde, could be the same for you too. Then start firefox (or any gtk app not working) with `GTK_USE_PORTAL=1 firefox`

To integrate those browsers into the desktop, there exists a package that is called plasma-browser-integration (again in arch). That won't fix the coredump but helps using it as well integrated default browser.

koffeinfriedhof wrote:Plasma4? I thought this is only running in some archaeological museums

So you're using two nvidia cards with two screens attached to every card? Or three/one? Lets try the following (if possible):
- uninstall the proprietary drivers (the system will use nouveau then)
- re/move the xorg.conf (look into xorg.conf.d too) to use the automatic detection system
- create a new, clean user without any configuration files
- Plasma5 login (not a wayland session) with this user, try the monitors overlap without moving them first to test the native layout behaviour. Does it overlap there too?
- After «playing around», set the arrangement as wanted and try again
- To test Wayland you could use sway, but then you must use nouveau.

again, thanks for your reply. I think I was too verbose in my previous post. I only mentioned Plasma4 because that what I was using with my Slackware14.2 distro release and I had problems with NVIDIA's Xinerama. Forget about Plasma4.

My current Plasma5/KDE (not Wayland) setup is using nouveau, Linux kernel 5.10. Two GTX 710 cards, two monitors on each card. Newly created user ... everything you suggested. I cannot use Wayland with this distro release. tried it, went very badly (no screens, no mouse/keyboard response ...).

Without moving the montors, they align horizontally as I specified in my OP:

[AOC 2060W , HDMI-1] [Teleliason IncVOX L19RCTN, VGA-1] [HP LV1911 HDMI-2] [Auria EQ166L, VGA-2]

There is no problem with this setup because all layout edges for each monitor touch the adjacent monitor. The problem on occurs when I move the Auria to sit above/center the reset of the monitors.

I don't know the GTX 710 chip, but you can check it using `lspci -nnk | grep -A3 "\[03..\]:" ` and compare the number with this page: https://nouveau.freedesktop.org/FeatureMatrix.html. Dual-head is nearly everywhere supported.

I didn't actual bother checking nouveau.freedesktop.org because I get quad monitors, no problem. It's only the re-arrangement of them with 'Display Configuration' that is giving me problems, and that is restricted to not being able to move the Auria monitor above the other three without showing either a gap between the upper/lower monitor or an overlap of the upper/lower monitor.

Firefox is not Qt5/KF based, so perhaps you need some gnome-packages to run it smoothly. I don't know which ones as I do neither use slackware nor firefox. You could try to run it using «portal»:
The packages in arch are called xdg-desktop-portal and xdg-desktop-portal-kde, could be the same for you too. Then start firefox (or any gtk app not working) with `GTK_USE_PORTAL=1 firefox`

To integrate those browsers into the desktop, there exists a package that is called plasma-browser-integration (again in arch). That won't fix the coredump but helps using it as well integrated default browser.

[/quote]
That's a good suggestion which I will keep in mind for down the road. Firefox works fine unless I run Xinerama, which is required if I use the NVIDIA driver and want to rearrange my monitors. The KDE 'Display Configuration' no longer works if using NVIDIA drivers. But having said that, I have not tried using NVIDIA drivers without Xinerama on the new system. I might try that, although I'm really trying to avoid using NVIDIA drivers. ... but, worth a shot.

What I'm looking for now is some elusive config that "remembers" the 'Display Configuration' other than the file in .local/share/kscreen. As I said, that one shows the upper monitor as "y"=0 no matter how I position it vertically. And the 'Display Configuration' remembers where I put it, regardless of the conf "y" setting.

So, my current research effort is to deteremine how Plasma5 remembers the monitor configuration (any ideas?), and I'm not planning on using NVIDIA drivers or Xinerama.

I've seen issues like this reported to bugs.kde.org. Maybe that should be something I do before spending much more time on this.

I did some more experimentation with the NVIDIA driver. Results:

1. I installed the latest NVIDIA driver for my GT 710 cards, no xorg.conf. This caused only two of my monitors to show in in 'Display Configuration' .

2. I re-installed the NVIDIA driver, this time with xorg.conf. Again, only two monitors showed in 'Display Configuration', but I ran the "NVIDIA X Server settings" utility, which showed the other two monitors disabled. I enabled them, which added the xorg.conf for a 2nd X screen, giving me 'X screen 0' and 'X screen 1', the latter having the 3rd and 4th monitors. Unfortunately, the 'Xscreen 1' overlaps 'Xscreen 0' and I cannot see the desktop on the lower (AOC) monitor. The only way around this is to use Xinerama which, as previously posted, does not work well with programs like Firefox and LibreOffice.

So, I'm reverting back to using the nouveau driver, no NVIDIA driver, which, with KDE, shows all 4 monitors and lets me arrange them all with 'Display Configuration' -- however, the gap/overlap problem persists. As mentioned, I can mitigate this by reducing the resolution on the top (Auria) monitor which still give a small overlap with the lower monitor, but I can live with that.

Unless you know of some other idea I could try I think my next step will be to post an issue on the bugs.kde.org site.

Okay, so I misunderstood your current configuration.

You'll find the configuration files in ~/.local/share/kscreen/UUID where the different layouts are stored. The monitor definitions are in the subfolder outputs/.

If you want to manual edit them, do it from another tty while logged out to not having overwritten your changes.

You'll find the configuration files in ~/.local/share/kscreen/UUID where the different layouts are stored. The monitor definitions are in the subfolder outputs/.

If you want to manual edit them, do it from another tty while logged out to not having overwritten your changes.

Already tried that. See the "Code" in my post of Mon Feb 15, 2021 5:14 pm.

However, very interesting! I think I've figured something out. After undoing the NVIDIA configuration and restoring the nouveau driver, and rebooting. I logged back in and went to my "Display Configuration'. As expected, all monitors were reset to their default horizontal positions. As before, I manually dragged them to the correct positions, but this time, the top (Auria) monitor was able to line up touching the top end of the bottom (AOC) monitor! Everything with those monitors is now working! No overlap. No gap. Why? ...

In looking at the ~/.local/share/kscreen/UUID config file, I see that the Auria monitor is now listed 2nd, not last as before. Now, the HP (rightmost) monitor is listed last. And guess what? Now I cannot align the bottom of the HP with the bottom of the two monitors to it's left. This I can live with.

So, conclusion, there is some kind of bug with the last-listed monitor in ~/.local/share/kscreen/UUID in that the arrangement for that monitor cannot be dragged to an absolute Y position aligning with the adjacent monitor's edge. It will either rest below, or some gap above the adjacent monitor border. Whether dragged to some gap above, or some gap below the adjacent monitor, the Y value in ~/.local/share/kscreen/UUID is always zero.

mfoley wrote:…there is some kind of bug with the last-listed monitor in ~/.local/share/kscreen/UUID …

Thats interesting. You can check this switching the plugs to create a new order and try again. If you can create a setup to reproduce this, create a bug report for it. I couldn't set this up in a virtual environment using qemu/kvm with a kde neon. Now that I know that it must be the last screen in config to be on top, I'll try again!

koffeinfriedhof wrote:

mfoley wrote:…there is some kind of bug with the last-listed monitor in ~/.local/share/kscreen/UUID …

Thats interesting. You can check this switching the plugs to create a new order and try again. If you can create a setup to reproduce this, create a bug report for it. I couldn't set this up in a virtual environment using qemu/kvm with a kde neon. Now that I know that it must be the last screen in config to be on top, I'll try again!

I'm not in front of that computer now, but next time I'm going to try adding a "dummy" monitor to the end of the list and see if that fixes it for monitor #4. probably not, but worth a try.

The idea of adding a dummy screen to the end of the ~/.config/local/kscreen/UUID file didn't work at all. When I logged in after trying that two of the monitors on my 2nd video card were disabled and, when I went to edit the config the dummy screen was removed. When I logged back in I got no screens. So, bad idea. I deleted the config file and let KDE create a new one from scratch.

Interesting, it turns out the position of the screen definition within the config file does not matter. In other messing around I found the Auria definition was in the 4th/last position in the config, but still had the bottom of that screen aligned with the top of the 2060W. Recall my screen positions:

Code: Select all

       [Auria]
[VOX]  [2060W]  [HP]


What does seem to cause the gap/overlap issue is the LAST screen I manipulate on System Settings > Display Configuration. Thus, from the default horizontal positioning, if I first move the Auria to the top, then the VOX to the left, then the HP to the right, the gap/overlap problem stays with the HP -- the last screen arranged -- I cannot align the bottom of the HP with the bottom of 2060W. Inspecting the config file still shows the order of definition as 2060W, VOX, HP, Auria. So, even though Auria is the last in the config file, it's the HP that has the problem -- the last screen arranged.

The good news is that in this case I can edit the config and change the HP's Y from 768 to 900 (matching the VOX) and now everything aligns properly.

Conclusion: there is some kind of bug with arranging the vertical position on the last monitor moved. If that last monitor is not located physically above the other (Y=0), the Y coordinate can be modified in the ~/.config/local/kscreen/UUID file.