anchor.diff:  # for Youtube support
   , quviSupport ? false, libquvi ? null
   , cacaSupport ? false, libcaca ? null
  -, vaapiSupport ? false, libva ? null }:
  +, vaapiSupport ? false, libva ? null
  +}:
   
   assert x11Support -> (libX11 != null && libXext != null && mesa != null && libXxf86vm != null);
   assert xineramaSupport -> (libXinerama != null && x11Support);
  
positive.code:   };
  }
  
  # Many thanks @matejc for this update: 0.5.0 and vaapi (experimental)
  
  # TODO: Wayland support
  # TODO: investigate libquvi problems (related to Youtube support)
  # TODO: investigate caca support
  
negative.code:     ++ optional cacaSupport libcaca
      ++ optional vaapiSupport libva
      ;
  
  # There are almost no need of "configure flags", but some libraries
  # weren't detected; see the TODO comments below
  