http://pub.cozmixng.org/~the-rwiki/rw-cgi.rb?cmd=view;name=RubyTkTut%3A%3A%A5%EA%A5%B9%A5%C8%A5%DC%A5%C3%A5%AF%A5%B9%A4%C8%A5%B9%A5%AF%A5%ED%A1%BC%A5%EB%A5%D0%A1%BC
scroll = TkScrollbar.new {
command proc { |arg| listbox.yview *arg }
pack('side' => 'right', 'fill' => 'y')
}

#listbox.configure('yscrollcommand' => proc { |arg| scroll.set *arg })
listbox.yscrollcommand(proc { |arg| scroll.set *arg })
で
warning: multiple values for a block parameter (2 for 1)
from c:/usr/bin/ruby/lib/ruby/1.8/tk.rb:1089

という警告がでまくるんですがどう書くのが正しいんでしょうか？