These functions provide access to a shared pool of Gtk2::Gdk::GC objects. When a new Gtk2::Gdk::GC is needed, Gtk2::Gdk::GC::get is called with the required depth, colormap and Gtk2::Gdk::GCValues. If a Gtk2::Gdk::GC with the required properties already exists then that is returned. If not, a new Gtk2::Gdk::GC is created. When the Gtk2::Gdk::GC is no longer needed, Gtk2::Gdk::GC::release should be called.
[From: http://developer.gnome.org/doc/API/2.0/gtk/gtk-Graphics-Contexts.html]
