plasma5 screen management going wrong

Duncan 1i5t5.duncan at
Fri Jul 13 07:35:10 BST 2018

Bug Reporter posted on Thu, 12 Jul 2018 22:00:58 -0400 as excerpted:

> The lack of powerdevil may be the showstopper in this process. So I
> started looking for a config file that might disable kscreen. I did not
> find any yet, but I did find kscreen-doctor. This might be the way to
> leave kscreen installed and to manage it the way one would manage
> screens with xorg conf files or with xrandr.
> Interestingly, `kscreen-doctor -i` tells me: Preferred KScreen backend :
> /usr/lib/qt/plugins/kf5/kscreen/
> I don't know exactly what that is, but the name gives me the feeling
> that kscreen-doctor might be able to be used like xrandr... any
> thoughts?

A *.so file indicates a "shared object", aka a "library", in MS Windows 
terms a DLL, dynamic-link-library.

The extension and API used here is RandR, Resolution and Rotation.  The X 
in front is because it's an X extension.

And the KSC is either kscreen or possibly KDE software collection, likely 
the former tho I'm not sure.

Presumably there's a different backend for wayland, this being the one 
for xorg.  (I'm guessing this is part of the libkscreen package, which as 
I said earlier I don't have installed/merged here, so I can't as easily 
look up what package it belongs to as I could were it installed. 

So basically is simply the KDE shared-object library 
wrapping the xorg RandR extension API that both kscreen and xrandr use.  

Meanwhile... [kscreen-doctor --help output snipped]

> I do not see a man page for kscreen-doctor and I don't see it discussed
> on any wikis. Does anyone here have any experience using it?
> I would like to know what the modes numbers mentioned above are. For
> example, what is mode 4 in "output.eDP-1.mode.4"?

I had come across kscreen-doctor at one point, but like you got a bit 
frustrated at the lack of documentation, tho as indicated it seems a CLI 
method of interacting with kscreen.

But for my purposes xrandr already did what I needed at the CLI, with 
plenty of documentation, so rather than mess around with the misbehaving 
kscreen and try to figure out kscreen-doctor some more, I just unmerged 
the whole thing and switched back to the generic X solution, xrandr while 
X was running, xorg.conf to configure how it starts up.  At least that 
way I had (a) something that worked pretty much as documented and as I 
needed, and (b) quite a bit of documentation to tell me how to convert 
what was in my head to the appropriate xrandr commandline and/or xorg.conf 

Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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