anchor.diff:  
         $client->waitForFile("/tmp/.X11-unix/X0");
   
  -      sleep 20;
  +      sleep 60;
   
         print STDERR $client->execute("DISPLAY=:0.0 xwd -root > /hostfs/$ENV{out}/screen.xwd");
       '';
  
positive.code:               home = "/home/alice";
                createHome = true;
                useDefaultShell = true;
              };
  
            environment.systemPackages = [ pkgs.xorg.xclock pkgs.xorg.xwd ];
  
negative.code:         { config, pkgs, ... }:
  
          { services.xserver.enable = true;
          
            services.xserver.displayManager.slim.enable = false;
            services.xserver.displayManager.kdm.enable = true;
            services.xserver.displayManager.kdm.extraConfig =
              ''
                [X-:0-Core]
                AutoLoginEnable=true
                AutoLoginUser=alice
                AutoLoginPass=foobar
              '';
              
            services.xserver.desktopManager.default = "kde4";
            services.xserver.desktopManager.kde4.enable = true;
  
            services.sshd.enable = true;
  
            users.extraUsers = pkgs.lib.singleton
              { name = "alice";
  