Black screen and Bad _NET_DESKTOP in xsessions-errors

[romatthe]

Problem Description

I'm trying to set up XMonad on my new NixOS setup with GDM as my display manager, but whatever I do I end up with a black screen and the inability to do anything.
When I look at my journalctl -b-1 I can see the following line several times:

Dec 23 08:12:24 nagoya xsession[1611]: Bad _NET_DESKTOP with data[0]=-1

Configuration File

I've reduces my config to the absolute minimum, so it appears the issue is not with anything in my configuration:

import XMonad

main = do
  xmonad $ defaultConfig
    { terminal    = myTerminal
    , modMask     = myModMask
    , borderWidth = myBorderWidth
    }

myTerminal    = "gnome-terminal"
myModMask     = mod4Mask
myBorderWidth = 3

I'm on NixOS, not sure if that matters. Here's my ultra-simple config:

{ config, pkgs, lib, ... }:
{
  # Enable the Gnome Desktop Environment.
  services.xserver.displayManager.gdm.enable = true;
  services.xserver.displayManager.gdm.wayland = false;
  services.xserver = {
    windowManager.xmonad = {
      enable = true;
      enableContribAndExtras = false;
      extraPackages = haskellPackages: [
        haskellPackages.xmonad
        haskellPackages.monad-logger
        haskellPackages.taffybar
      ];
    };
    windowManager.default = "xmonad";
  };
}

[geekosaur]

The Bad _NET_DESKTOP message comes from a program attempting to make a window "sticky"; we don't currently handle this form of message.