gnome-flashback: fix screenshot key and screen not locking when idle

[gazally]

These auto-started services are failing to start in the gnome-flashback desktop manager service, leaving warnings in the log:

gnome-flashback-clipboard
gnome-flashback-idle-monitor
gnome-flashback-media-keys

Fix the failures by removing the line from postInstall in the gnome-flashback package which is deleting the executables for those services, which the build creates in $out/libexec.

gnome-flashback-idle-monitor is responsible for sending a dbus message when the system is idle, so without it the screen never dims or locks. When gnome-flashback-media-keys is not running, using the PrtScr key to grab screenshots does not work.

gnome-flashback-clipboard from my cursory inspection of its source deals with streaming large clipboard transfers and translating clipboard formats. I have had copy and paste fail to work on my system before this fix, and haven't seen the problem since, but I don't have a reproducible case.

There's one more warning in the log about gnome-flashback-nm-applet failing to start, but the executable for that one is not present in $out/libexec so it seems to be a separate issue.

Description of changes

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.05 Release Notes (or backporting 22.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[bobby285271]

LGTM 🙃

@ofborg test gnome-flashback

I applied this PR to dd3626c and things became very reasonable to me, at that time there are only two bash scripts in libexec named gnome-flashback-{compiz,metacity} and both calls gnome-session. Since #53695 wants to support custom sessions, things are re-implemented in writeShellScriptBin and nothing in libexec are useful anymore.

I believe in this case there are no reasons to drop gnome-flashback-{clipboard,idle-monitor,media-keys}. I am using this PR and I can (at least) confirm the screenshot key issue is fixed. The only things is that we are re-adding libexec/gnome-flashback-metacity, with a quick look I don't aware of anything that will try exec that so we should be safe.

There's one more warning in the log about gnome-flashback-nm-applet failing to start

Looks like it looks for nm-applet (in networkmanagerapplet), but sounds like some people don't like adding that to desktop modules 😕

[jtojnar]

I would probably still remove gnome-flashback-{compiz,metacity} since having it and not being used can be confusing (e.g. people can try patching it to no effect).

[bobby285271]

Hi @gazally, I force-pushed your branch to apply the suggestions above (and also updated the commit message) 🙇

(gnome-flashback-compiz is gone these days)

[github-actions]

Successfully created backport PR for release-23.05:

• [Backport release-23.05] gnome-flashback: fix screenshot key and screen not locking when idle #235302