gtk.rb

require 'gtk2'

window = Gtk::Window.new
window.signal_connect('destroy') { Gtk.main_quit }

main_box = Gtk::HBox.new(false, 2)
left_box = Gtk::VBox.new(false, 2)
right_box = Gtk::VBox.new(false, 2)
button = Gtk::Button.new("test")
button2 = Gtk::Button.new("test2")

left_box.pack_start(button, true, true, 0)
right_box.pack_start(button2, true, true, 0)
main_box.pack_start(left_box, true, true, 0)
main_box.pack_start(right_box, true, true, 0)

window.add(main_box)
window.show_all
Gtk.main