anchor.diff:  
     configureFlags = [
       "--${boolEn documentationSupport}-documentation"
  -    "--${boolEn eventGUISupport}-event-gui"
  +    "--${boolEn debugGUISupport}-debug-gui"
       "--${boolEn testsSupport}-tests"
     ];
   
  
positive.code:     libwacom
      mtdev
      systemd_lib
    ] ++ optionals eventGUISupport [
      cairo
      glib
      gtk3
  
negative.code: , documentationSupport ? false
    , doxygen ? null
    , graphviz ? null
   # GUI debug viewer support
  , debugGUISupport ? false
    , cairo ? null
    , glib ? null
    , gtk3 ? null
  