anchor.diff:  
   in
   
  -{
  +mkIf cfg.enable {
     require = [
       options
  +    copyOldOptions
     ];
   
     services = {
  
positive.code: let
    inherit (pkgs.lib) mkOption;
  
    options = { services = { xserver = {
  
      slim = {
  
        theme = mkOption {
          default = null;
          example = pkgs.fetchurl {
            url = http://download.berlios.de/slim/slim-wave.tar.gz;
            sha256 = "0ndr419i5myzcylvxb89m9grl2xyq6fbnyc3lkd711mzlmnnfxdy";
          };
          description = "
            The theme for the SLiM login manager.  If not specified, SLiM's
            default theme is used.  See <link
            xlink:href='http://slim.berlios.de/themes01.php'/> for a
            collection of themes.
          ";
        };
  
        defaultUser = mkOption {
          default = "";
          example = "login";
          description = "
            The default user to load. If you put a username here you
            get it automatically loaded into the username field, and
            the focus is placed on the password.
          ";
        };
  
        hideCursor = mkOption {
          default = false;
          example = true;
          description = "
            Hide the mouse cursor on the login screen.
          ";
        };
      };
  
    }; /* xserver */ }; /* services */ };
  
negative.code: let
    xcfg = config.services.xserver;
    dmcfg = xcfg.displayManager;
    cfg = dmcfg.slim;
  
    inherit (pkgs.lib) mkIf;
  
    slimConfig = pkgs.writeText "slim.cfg" ''
      xauth_path ${dmcfg.xauthBin}
  