anchor.diff:      fontconfig
       freetype
       glib
  -    gnome2.GConf
  -    gnome2.gdk_pixbuf
  -    gnome2.gtk
  -    gnome2.pango
  +    gnome3.gconf
  +    gdk_pixbuf
  +    gtk3
  +    pango
       libnotify
       libxcb
       nspr
  
positive.code: { stdenv, fetchurl, dpkg
  , alsaLib, atk, cairo, cups, curl, dbus, expat, fontconfig, freetype, glib
  , gnome2, libnotify, libxcb, nspr, nss, systemd, xorg }:
  
  let
  
    version = "3.1.0";
  
    rpath = stdenv.lib.makeLibraryPath [
      alsaLib
  
negative.code:     if stdenv.system == "x86_64-linux" then
        fetchurl {
          url = "https://downloads.slack-edge.com/linux_releases/slack-desktop-${version}-amd64.deb";
          sha256 = "0497794a7f0e5ac00a9421e6b1875dcc576ed93efc4a7d8c6465db641c234064";
        }
      else
        throw "Slack is not supported on ${stdenv.system}";
  