title: Use glade with pygobject Gtk3
body: <p>I am converting a script to use Gtk3 using the migration guide (<a href="http://live.gnome.org/PyGObject/IntrospectionPorting#Porting_from_PyGTK_2_to_PyGI_GTK_3">Porting GTK2 to GTK3</a>). I converted my <code>import pygtk</code> to a <code>from gi.repository import Gtk</code> and so on...</p>
  
  <p>I'm stuck because the glade module was loaded from module gtk:</p>
  
  <pre><code> import gtk
   import gtk.glade
  </code></pre>
  
  <p>but there's no way now to do that anymore.</p>
  
  <p>Note that I would only need a replacement for <code>gtk.glade.XML()</code>...</p>