Bug 356905

open konsole and run
    ps ax | grep kwin
    kwin_x11 --version
    qdbus | grep -i kwin

and post the output.

This
> No such method 'compositingNotPossibleReason' in interface 'org.kde.KWin' at object path '/KWin' (signature '')

indicates that kwin simply isn't running at all (but maybe NixOS configured another default WM like openbox?)

Hi Thomas!  No, this is not a case.

$ ps ax | grep kwin
 1060 ?        Sl     4:24 kwin_x11

$ kwin_x11 --version
kwin 5.3.2

$ qdbus | grep -i kwin
 org.kde.KWin
 org.kde.kwin.Screenshot

On a close look
> No such method 'compositingNotPossibleReason' in interface 'org.kde.KWin' at object path '/KWin' (signature '')

Looks like it's the KDE4 kcm (the compositor stuff is presently in /Compositor"

Can you run "kcmshell5 kwincompositing"?

It opened me a configuration window.  I changed Xrender to OpenGL, antialiasing method and set window preview for minimized windows, then applied changes.  Now, window preview indeed works for minimized windows, but I still have no luck with desktop effects.

By the way, I'm finding customization in KDE 5 quite odd, e.g. to configure locales I have to open settings window right clicking on locale indicator and selecting "Settings" from context menu rather than doing this in "System Settings"; same for date and time settings and I still can't switch my clock appearance to 12-hours format.  I suppose this will change in near future, won't it?

(In reply to Arthur Fayzrakhmanov from comment #4)
> It opened me a configuration window.  I changed Xrender to OpenGL,
> antialiasing method and set window preview for minimized windows, then
> applied changes.  Now, window preview indeed works for minimized windows,
> but I still have no luck with desktop effects.

kcmshell5 kwineffects (close the other dialog before or you get an "already opened" error)
It seems the distro ships kwin 4 config modules along kwin 5 and/or both kwin versions and unconditionally loads kwin4 config modules and/or there're eg. systemsettings4 and systemsettings5 (and you use the former on KDE5)

Distro problem for now (installing kwin4 in parallel to kwin5 - or any plasma/kde workspace - isn't officially supported upstream. It seems possible, but it's quite some effort required downstream to keep them apart, afaik OpenSuSE is *trying* ;-) to do that to quite some success)

Maybe, I should fire a report on NixPkgs tracker, because the way I install KDE is just simply:

1. add to my system config
services.xserver.displayManager.sddm.enable = true;
services.xserver.desktopManager.kde5.enable = true;

2. and then I just rebuilding my system with `nixos-rebuild switch` command.

So (I believe) the only way to control this is to make changes to nix-expression from channel.

kcmshell5 kwineffects - Voila!  This is the right dialog to configure effects!  Thank you, I've just tested fuzzy windows and it's working.  So, it turns that all KDE5 settings are "hidden", I mean System Settings does not allow me to change configuration.  Rather than that I need to use `kcmshell5` to open "right" dialogs.  I've run `kcmshell5 --list` and this shows me a lot of options, great!  But why these dialogs not available from KMenu?

Finally, this issue can be closed, because desktop effects works indeed.  I guess that I have KDE4 "System Settings" in KMenu and the question is actually "why?" and "where to find KDE5 one?".

Thank you pal!

Do you have a "systemsettings5" binary? ("which systemsettings5" in konsole)

Wow!  Surprisingly I do!  And also I have correct binary in KMenu, but for some reason I have another instance of systemsettings in my KMenu favorites, which opens KDE4 settings.  Very odd.  Thank you again, without you're assistance I will never sort this out.