plasma-workspace: add systementry sessionmanagement patch

[picnoir]

Motivation for this change

Systemd v246 hides the interface used by KDE to fetch the user session
details. We're applying this commit from 5.19.90 upgrading the
systementry applet to use the new sessionmanagement API.

Because of this API breakage, the "Switch User" item was absent from
the KDE application laucher.

See the #98141 issue for the
full story.

Things done

Pick https://invent.kde.org/plasma/plasma-workspace/-/commit/05414ed58d43d87d907326636faac53ae2e7bd60 from upstream.

The missing items are appearing again and are fully functional.

How to Test?

I used this trick #98141 (comment).

Don't forget to point to your local nixpkgs checkout:

mid=$(nixops create nixops-kde-test.nix)
nixops modify -d $mid -I nixpkgs=/path/to/your/checkout nixops-kde-test.nix
nixops deploy -d $mid

Note for @ttuegel: I'll let you handle the backport (if you're ok with this PR ofc :)).

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[ttuegel]

We should use fetchpatch instead of fetchurl.

[ttuegel]

@NinjaTrappeur Does this also fix the lock screen?

[picnoir]

Does this also fix the lock screen?

I did not check the lock screen, I only verified the item was appearing in the login screen and application launcher.

I destroyed the VM and garbage collected the store. I think I'll call it a day for now.

I'll check this tomorrow night CEST (if you cannot do it by then).

PTAL.

[ttuegel]

The launcher is fixed, but the lock screen is not fixed. I guess that we need a patch to kscreenlocker, too.

[jonringer]

This may be hacky since there's not a good "Qt source of truth", but would we be able to conditionally disable this, something like:

] ++ lib.optional (lib.versionOlder qtquickcontrols.version "5.19") [
  <patch>
 ];

[jonringer]

actually, the Qt PRs will probably visit this, and might not be necessary.

Too much time spent doing python PRs :)

[jonringer]

seems like no regressions from a program standpoint. Haven't tested

https://github.com/NixOS/nixpkgs/pull/99582
3 packages marked as broken and skipped:
libsForQt5.khotkeys libsForQt512.khotkeys libsForQt515.khotkeys

16 packages built:
kde-cli-tools kdeplasma-addons kdev-php kdev-python kdevelop kdevelop-unwrapped kmenuedit krohnkite kwin-dynamic-workspaces kwin-tiling plasma5.khotkeys plasma-desktop plasma-workspace powerdevil systemsettings wacomtablet

[picnoir]

Indeed, I can also reproduce the problem on the lockscreen. I don't see any fix upstream be it in code or as a related bugtracker ticket.

I need help here, there's a hole in my understanding of kde-workspace.

As far I understand, the item visibility is defined at https://invent.kde.org/plasma/plasma-workspace/-/blob/master/lookandfeel/contents/lockscreen/LockScreenUi.qml#L277

The sessionsModel.canSwitchUser is the right way to get the capability, I don't see anything wrong :/

However, this action item is clearly not visible. Meaning either sessionsModel.canStartNewSession or sessionsModel.canSwitchUser is not verified in our context.

Any idea what could happen here @ttuegel? Are you in contact with some upstream dev. They might be able to help here.

I'd be interested to see if your systemd patch fixes this issue. If it is, I guess we should investigate the sessionsModel.canSwitchUser implementation.

[picnoir]

Fixed by #99629