anchor.diff:      "--disable-beos"
       "--disable-drm"
       "--disable-gallium"
  -    "--enable-libpng"
  -    "--enable-gl"
  -    "--disable-glesv2"
  -    # FIXME: cogl recursion
  -    "--disable-cogl"
  +    (enFlag "libpng" (libpng != null) null)
  +    # Only one OpenGL backend may be selected at compile time
  +    # OpenGL X (gl), or OpenGL ES 2.0 (glesv2)
  +    (enFlag "gl" (!gles2) null)
  +    (enFlag "glesv2" gles2 null)
  +    "--disable-cogl" # recursive dependency
       # FIXME: fix directfb mirroring
       "--disable-directfb"
       "--disable-vg"
  -    "--enable-egl"
  -    "--enable-glx"
  +    (enFlag "egl" (mesa_noglu != null) null)
  +    (enFlag "glx" (mesa_noglu != null) null)
       "--disable-wgl"
       "--enable-script"
       "--enable-ft"
  
positive.code:     sha256 = "0lmjlzmghmr27y615px9hkm552x7ap6pmq9mfbzr6smp8y2b6g31";
    };
  
    configureFlags = [
      "--disable-gtk-doc"
      "--disable-gtk-doc-html"
      "--disable-gtk-doc-pdf"
      "--disable-gcov"
      "--disable-valgrind"
      "--enable-xlib"
      "--enable-xlib-xrender"
      "--enable-xcb"
      "--enable-xlib-xcb"
      "--enable-xcb-shm"
      # TODO: qt
      "--disable-qt"
      "--disable-quartz"
      "--disable-quartz-font"
  
negative.code: { stdenv
  , autoreconfHook
  , fetchTritonPatch
  , fetchurl
  , libiconv
  
  , cogl
  , fontconfig
  , freetype
  , glib
  