Oh sorry, currently this library only run on linux. I don't put
#If Not TargetLinux because I think everybody knows Gtk is linux library. My bad.
In this page https://www.gtk.org/download/macos.php , there is Gtk for Mac. But, I don't have Mac. So, I don't know dylib name of gtk shared library on Mac.
You can check Gtk+2 library on your system and replace
Gtk2Lib constant value with the dylib name.