This library is called gtk_module. It extends the Gtk/Gdk part of ruby-gnome2. It also contains several add-on colours, in the file gtk_colours.rb These colours can be used like so: include Gtk::Colours MEDIUMAQUAMARINE The constants correspond to the "typical" html colours, just in an upcased variant, so we have things like SLATEBLUE PALEGREEN ORCHID and so on. The idea behind this library here is to make the ruby-gnome bindings more "ruby-like" rather than have them a 1:1 mapping. I also use some custom widgets.