SDDM multi-screen madness

[oshunluvr]

This is such a small and barely noticeable issue, feel free to skip to the next topic...

IME SDDM has always shown on all screens and the greeter cursor seems to always be on a secondary monitor and never on the one in front of me - my second is to the right of the primary.

Before switching to Wayland, I was able to turn off the second monitor via SDDM X11 configuration so the greeter sat in front of me while the secondary monitor was off. Then when logging in, the second monitor would turn on and desktop loads, etc. Worked like a charm.

Since the last KDEneon update I've been on Plasma and Wayland so the X11 settings in SDDM no longer apply. I am back to the dual screen greeter with the cursor to my right. Sigh...

This morning I updated to 6.0.2 and rebooted. I was on my phone so I didn't immediately log in and the greeter timed out. When I wiggled the mouse the greeter reappeared as expected but ONLY ON SCREEN 2!

What kind of madness is this?

I'm going to log out to see if it repeats. I'm half inclined to attach a couple more monitors just so see what happens.

It occurs to me that this might mean there is some hope that I can make SDDM behave the way I want when using Wayland. Off to the land of the internet...

[oshunluvr]

OK so here's what I've observed:

When the greeter screens initially appear after boot up the mouse cursor sits right in the middle of the two screens. If I click the mouse the login cursor follows the mouse. It seems to be on monitor 2 because the mouse is ever so slightly to the right of center.

Logging out and letting the greeter time out happens at different times - on one monitor the greeter drops off a few seconds before the other.

Moving the mouse brings up the greeter on the screen the mouse cursor is on, but then the second one comes up also a few seconds later.

So there is some independent activity within the greeter. Cursor follows the mouse as expected.

[claydoh]

SDDM runs independently from your desktop session, so it normally runs xorg until the user logs in, and whatever session is chosen takes over.

As far as I can tell, SDDM should still be using an xorg session instead of kwin-wayland, but I can't tell, or know how to tell which it is. SDDM had a rare update right at Plasma 6 launch that neon also added, but the changelog doesn't mention using a wayland session as the default.

You might try telling sddm to explicitly use an xorg session just to get your old functionality back:

Create a file /etc/sddm.conf.d/force_x11.conf, or whatever name you'd like, with:

[General]
DisplayServer=x11​

Then, you should be able to use xrandr to set your screens as you were, previously. Assuming that SDDM is actually running using wayland, and it isn't some new bug in sddm.

I *still* haven't discovered how to replicate xrandr to do things like this, or rather where to put them. I know it is kscreen-doctor, but I haven't spent any time figuring it out. Having the login on both my monitors doesn't bug the crap out of me like it used to, for some reason.

I AM annoyed that support for many/most third party themes is broken, since they don't support Qt6


....and I just got word that is using xorg at the login, unless one sets it manually (me, for testing). So why would your xrandr commands stop working......

I wonder if this setting means "wayland on sddm" or not :




And of course I have no idea if this actually works, it sure doesn't for me, and I have set wayland in my sddm config, even using this after disabling one of my monitors.

[Schwarzer Kater]

Very interesting info about sddm, thanks.

OT:

[…]
I AM annoyed that support for many/most third party themes is broken, since they don't support Qt6
[…]

This was to be expected, wasn't it?
And I am sure that the good ones are already working on their themes (in fact there already are several themes for Plasma 6 - nothing for your taste amongst them?).

[oshunluvr]

I guess I assumed since SDDM has Wayland options in it's configs it ran in Wayland or X11. Webbing a bit and it looks like it will run in Wayland if you configure it that way. One of the last upgrades replaced my /usr/share/sddm/scripts/Xsetup with an unedited version so my monitor control was lost.

However, this begs a question: If SDDM runs an X11 command that shuts off one monitor and then launches the desktop in Wayland mode, how does one turn that monitor back on?

The command in Xsetup was:

xrandr --output DisplayPort-0 --mode 3840x2160 --pos 0x0 --output DisplayPort-1 --off

and the command in my .profile was:

xrandr --output DisplayPort-0 --primary --mode 3840x2160 --pos 0x0 --output DisplayPort-1 --mode 3840x2160 --pos 3840x0

So does Wayland just take over and turn the second monitor back on?

[claydoh]

However, this begs a question: If SDDM runs an X11 command that shuts off one monitor and then launches the desktop in Wayland mode, how does one turn that monitor back on?

Your user account's desktop settings kick in. This was how it worked for me, when I was using xrandr in my sddm config, but my usual Wayland desktop. Same thing happens if you were logging in to an xorg desktop.

The xorg session that sddm (or whatever login manager) uses is separate from the user's xorg session

[claydoh]

This was to be expected, wasn't it?
And I am sure that the good ones are already working on their themes (in fact there already are several themes for Plasma 6 - nothing for your taste amongst them?).

No-ish.
I am talking about SDDM themes here, not Plasma themes. Note many/most of the Plasma 6 ready Global Themes don't seem to include matching SDDM themes. And , no I don't really like any of the global themes (I mainly just change the Plasma Style for panel/widget styling, I don't change anything else other than accent color from the wallpaper)

And the SDDM theme from one "plasma 6" global theme (Utterly Nord) is NOT plasma 6/qt6 capable.
Now, I am not complaining that much, it probably won't be hard to convert these to Qt6, since they are just qml, no compiling or anything. But quite a few of these are based on an old theme called Sugar that is highly configurable (hence the preponderance of themes based on it, and why I use one). These probably will be harder to re-do.

[Schwarzer Kater]

OT:
claydoh: Sorry, I misunderstood you. You are right: there currently is a lack of SDDM themes for Plasma 6. And there is no own category for Plasma 6 SDDM themes either. I only saw one or two with the statement "In the process of being ported to Plasma 6"… I guess we will have to wait and see.
I don't like complete themes that much either - taking the default Breeze/Plasma designs mainly as a basis normally is good enough for me.