Gnome Flashback with XMonad on NixOS

flashback-xmonad.nix

{

services.displayManager.extraSessionFilePackages =
  let gnome-flashback-xmonad = pkgs.callPackage ({ stdenv, gnome3, bash, haskellPackages, glib, wrapGAppsHook }: stdenv.mkDerivation {
    name = "gnome-flashback-xmonad";

    buildInputs = [ gnome3.gnome-flashback gnome3.gnome-panel bash haskellPackages.xmonad glib ];
    nativeBuildInputs = [ wrapGAppsHook ];

    unpackPhase = "true";

    installPhase = ''
      mkdir -p $out/libexec
      cat << EOF > $out/libexec/gnome-flashback-xmonad
      #!${bash}/bin/sh

      if [ -z \$XDG_CURRENT_DESKTOP ]; then
        export XDG_CURRENT_DESKTOP="GNOME-Flashback:GNOME"
      fi

      exec ${gnome3.gnome-session}/bin/gnome-session --session=gnome-flashback-xmonad --disable-acceleration-check "\$@"
      EOF
      chmod +x $out/libexec/gnome-flashback-xmonad

      mkdir -p $out/share/gnome-session/sessions
      cat << 'EOF' > $out/share/gnome-session/sessions/gnome-flashback-xmonad.session
      [GNOME Session]
      Name=GNOME Flashback (XMonad)
      RequiredComponents=xmonad;gnome-flashback-init;gnome-flashback;gnome-panel;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Clipboard;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Mouse;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;org.gnome.SettingsDaemon.XSettings;
      EOF

      mkdir -p $out/share/applications
      cat << 'EOF' > $out/share/applications/xmonad.desktop
      [Desktop Entry]
      Type=Application
      Encoding=UTF-8
      Name=Xmonad
      Exec=${haskellPackages.xmonad}/bin/xmonad
      NoDisplay=true
      X-GNOME-WMName=Xmonad
      X-GNOME-Autostart-Phase=WindowManager
      X-GNOME-Provides=windowmanager
      X-GNOME-Autostart-Notify=false
      EOF

      mkdir -p $out/share/xsessions
      cat << EOF > $out/share/xsessions/gnome-flashback-xmonad.desktop
      [Desktop Entry]
      Name=GNOME Flashback (XMonad)
      Comment=This session logs you into GNOME Flashback with XMonad
      Exec=$out/libexec/gnome-flashback-xmonad
      TryExec=${haskellPackages.xmonad}/bin/xmonad
      Type=Application
      DesktopNames=GNOME-Flashback;GNOME;
      EOF
    '';
  })
  {};
  in [ gnome-flashback-xmonad ];
  
}

@shiqicao hey, support has been merged to nixpkgs, check out the gnome.flashback options:

https://search.nixos.org/options?channel=22.11&from=0&size=50&sort=relevance&type=packages&query=Flashback