请问这个ruby-gtk出现什么问题了？

Question

请看
http://ruby-gnome2.sourceforge.jp/hiki.cgi?tut-gtk-signals-more
% irb --simple-prompt
>> require 'gtk2'
=> true
>> b = Gtk::Button.new("hoge")
=> #<Gtk::Button:0x40a2a858 ptr=0x8237df8>
>> b.signal_connect("clicked") { puts 1 }
=> 1
>> b.signal_connect("clicked") { puts 2 }
=> 2
>>
我自己的测试
pt@pt-laptop:~$ irb
irb(main):001:0> require  'rubygems'
=> true
irb(main):002:0> require  'gtk2'
=> true
irb(main):003:0>  b = Gtk::Button.new("hoge")
=> #<Gtk::Button:0xb750b72c ptr=0x9114498>
irb(main):004:0> b.signal_connect("clicked") { puts 1 }
=> 9
irb(main):005:0>  b.signal_connect("clicked") { puts 2 }
=> 10
问题在哪里？