gistfile1.txt

#!/usr/bin/ruby

'''
ZetCode Ruby GTK tutorial

This program centers a window on 
the screen.

Author: Jan Bodnar
Website: www.zetcode.com
Last modified: May 2014
'''

require 'gtk3'

class RubyApp < Gtk::Window

  def initialize
    super

    set_title "Center"
    signal_connect "destroy" do
      Gtk.main_quit
    end

    set_default_size 300, 200

    set_window_position Gtk::Window::Position::CENTER

    show
  end
end

Gtk.init
window = RubyApp.new
Gtk.main