Bug 389016

Just had a chance to check the X session and primary display is saving properly there.  

So, under the X session, primary display is saved by the KCM, under Wayland session, it is not.

The problem is that Primary Display is not a thing in Wayland. We haven't entirely made up our mind what we want it for, so that is a bit in limbo. As KScreen reads the actual screen setup, and not just a config file, it's expected (but not intuitive) that the primary display setting won't be saved.

What do you want to achieve by setting the primary display?

Ok, makes sense.  I naively assumed that primary display meant "the display where stuff goes first" (panels, windows, dockers, etc.) as displays may come and go.

I am writing a little plasmoid that allows for basic display management (enable/disable, rez/ref change, orientation, etc.) and I was trying set primary display as a default based on user selection when a known monitor comes back on (enables).  

However, I see your point.  With the "Active Screen follows Mouse" option and the ability to interact when screen config changes (enable/disable), "primary display" seems superfluous.

Right, good to know. Also very good that I asked that question, because I've been working on something very similar. If you hit me up on IRC or by email I can show you what I already have, might save you some work.

I'll close this bugreport for now, since it doesn't add much tracking this in a bugreport as long as we haven't decided what to do with it at all.

Sorry, if I bring this up again, but afaics, this is the original bug for this.
bug 390638 and bug 392578 seem duplicates.

(In reply to Sebastian Kügler from comment #2)
> The problem is that Primary Display is not a thing in Wayland. We haven't
> entirely made up our mind what we want it for, so that is a bit in limbo. As
> KScreen reads the actual screen setup, and not just a config file, it's
> expected (but not intuitive) that the primary display setting won't be saved.
> 
> What do you want to achieve by setting the primary display?

I recently decided to give Plasma (Wayland) a try again and it mostly works fine so far, but this thing here really is a set-back.

I've got a multi-screen setup with two screens of which one is the primary screen (in the meaning how I use it) and I want the desktop widget, panel etc. to appear there.
For some reason (and this seems completely random), plasma decides that the other screen is preferred and I can't change it.

Sure, I could move the panel and stuff to the other screen, but this seems tedious (multiple to many steps, depending on the layout) and actually completely unnecessary, if you could actually solve it by defining a primary output.
In addition, I have the problem that the application dashboard, which I really like, cannot be moved to the other screen.
It will always open on the screen that plasma decided to be the default screen.
This is a showstopper for me, because after getting used to the dashboard, I can't really use the other two menu options anymore and for various reasons, I can't really use the dashboard on the second screen as is as well.

But ok, that's just me. Now for the actual reason why I deem something like this really important.
At work, I'm using a laptop computer with a relatively small display on Windows.
Windows, btw, does have a "main screen" setting (not sure if it's actually called like that, but it's there) and it works great.
I use that laptop commonly with different screen configurations, especially:
1. Only the laptop display: laptop display should be main screen
2. laptop display + external display: now I want to have the panel on the bigger screen, which would be impossible to set up in plasma/wayland right now.
3. laptop display + 2 external displays: in addition to 2. I want to be able to select on which display the panel shows up.

Note that the panel shouldn't be specific to a certain monitor. That again would be tedious to setup.

Another usecase: if you e.g. have a beamer or TV connected to the computer and extend the desktop to that beamer, you don't want that to end up as the default screen, hence a setting to prefer the other screen would really help here.

*** Bug 425795 has been marked as a duplicate of this bug. ***