anchor.diff:  { lib
   , mkDerivation
   , fetchurl
  -, fetchpatch
   , variant ? "standalone"
   , fetchFromGitHub
   , cmake
  
positive.code:     "-DGMIC_QT_HOST=${if variant == "standalone" then "none" else variant}"
    ];
  
    postFixup = lib.optionalString (variant == "gimp") ''
      echo "wrapping $out/${gimp.targetPluginDir}/gmic_gimp_qt"
      wrapQtApp "$out/${gimp.targetPluginDir}/gmic_gimp_qt"
  
negative.code:     ./fix-gimp-plugin-path.patch
    ];
  
    nativeBuildInputs = [
      cmake
      pkg-config
  