anchor.diff:    postInstall = ''
       wrapProgram $out/bin/FreeCAD --prefix PYTHONPATH : $PYTHONPATH \
         --set COIN_GL_NO_CURRENT_CONTEXT_CHECK 1
  -
  -    mkdir -p $out/share/mime/packages
  -    cat << EOF > $out/share/mime/packages/freecad.xml
  -    <?xml version="1.0" encoding="UTF-8"?>
  -    <mime-info xmlns='http://www.freedesktop.org/standards/shared-mime-info'>
  -      <mime-type type="application/x-extension-fcstd">
  -        <sub-class-of type="application/zip"/>
  -        <comment>FreeCAD Document</comment>
  -        <glob pattern="*.fcstd"/>
  -      </mime-type>
  -    </mime-info>
  -    EOF
  -
  -    mkdir -p $out/share/applications
  -    cp $desktopItem/share/applications/* $out/share/applications/
  -    for entry in $out/share/applications/*.desktop; do
  -      substituteAllInPlace $entry
  -    done
     '';
  -
  -  desktopItem = makeDesktopItem {
  -    name = "freecad";
  -    desktopName = "FreeCAD";
  -    genericName = "CAD Application";
  -    comment = meta.description;
  -    exec = "@out@/bin/FreeCAD %F";
  -    categories = "Science;Education;Engineering;";
  -    startupNotify = "true";
  -    mimeType = "application/x-extension-fcstd;";
  -    extraEntries = ''
  -      Path=@out@/share/freecad
  -    '';
  -  };
  -
  +    
     meta = with stdenv.lib; {
       description = "General purpose Open Source 3D CAD/MCAD/CAx/CAE/PLM modeler";
       homepage = https://www.freecadweb.org/;
  
positive.code:   ] ++ (with pythonPackages; [
      matplotlib pycollada pyside pysideShiboken pysideTools pivy python boost
    ]);
  
    patches = [
      # Fix for finding boost_python. Boost >= 1.67.0 appends the Python version.
      (fetchpatch {
        url = https://github.com/FreeCAD/FreeCAD/commit/3c9e6b038ed544e446c61695dab62f83e781a28a.patch;
        sha256 = "0f09qywzn0y41hylizb5g8jy74fi53iqmvqr5zznaz16wpw4hqbp";
      })
    ];
  
    enableParallelBuilding = true;
  
  
negative.code:   pythonPackages = python27Packages;
  in stdenv.mkDerivation rec {
    name = "freecad-${version}";
    version = "0.18.1";
  
    src = fetchurl {
      url = "https://github.com/FreeCAD/FreeCAD/archive/${version}.tar.gz";
      sha256 = "0lamrs84zv99v4z7yi6d9amjmnh7r6frairc2aajgfic380720bc";
    };
  
    buildInputs = [ cmake coin3d xercesc ode eigen qt4 opencascade gts
  