{ config, pkgs, lib, ... }:
{
  # Import unstable with niv.
  nixpkgs.config.packageOverrides = pkgs: {
    unstable = import (import ../nix/sources.nix).unstable {
      inherit pkgs;
    };
  };

  users.users.yoda = {
    packages = with pkgs; [
      signal-desktop-beta # Signal client
    ];
  };
#  users.users.yoda = {
#    packages = with pkgs.unstable; [
#      signal-desktop-beta # Signal client
#    ];
#  };

  # TODO: lib.mkIf (config.services.xserver.displayManager.gdm.wayland)

  # TODO: Signal on Wayland without crash.
  # Signal does also use the NIXOS_OZONE_WL variable to enable Wayland support.
  # However, it does currently crash in this mode.
  # See
  #  https://github.com/stelcodes/nixos-config/commit/79071d30912c5b6c2560654925bcc98533cf758f
  #  https://github.com/NixOS/nixpkgs/pull/222163
  #  https://github.com/NixOS/nixpkgs/issues/261101
  #  https://github.com/NixOS/nixpkgs/blob/898cb2064b6e98b8c5499f37e81adbdf2925f7c5/pkgs/applications/networking/instant-messengers/signal-desktop/generic.nix#L155



  # Wayland support:
  # Temporary fix until the above TODO is resolved.
  #
  # The following worked multiple times with signal-desktop-beta
  # ... But sometimes it crashes on startup.
  # signal-desktop-beta --use-tray-icon --enable-features=UseOzonePlatform --ozone-platform=wayland
  #
  # https://github.com/NixOS/nixpkgs/issues/222043#issuecomment-1493457041
 nixpkgs.overlays = [
   (self: super: {
     signal-desktop-beta = super.signal-desktop-beta.overrideAttrs (old: {
       preFixup = old.preFixup + ''
         gappsWrapperArgs+=(
           --add-flags "--enable-features=UseOzonePlatform"
           --add-flags "--ozone-platform=wayland"
         )
       '';
     });
   })
 ];
#  nixpkgs.overlays = [
#    (self: super: {
#      unstable.signal-desktop-beta = super.unstable.signal-desktop-beta.overrideAttrs (old: {
#        preFixup = old.preFixup + ''
#          gappsWrapperArgs+=(
#            --add-flags "--enable-features=UseOzonePlatform"
#            --add-flags "--ozone-platform=wayland"
#          )
#        '';
#      });
#    })
#  ];
}