require 'gtk'

window = Gtk::Window.new(Gtk::WINDOW_TOPLEVEL)
hbox = Gtk::HBox.new(false, 0)

button1 = Gtk::Button.new('Hello World')
button2 = Gtk::Button.new('button2')

hbox.pack_start button1, true, true, 0
hbox.pack_start button2, true, true, 0

window.add hbox
button1.show
button2.show
hbox.show
window.show
Gtk.main