title: Unable to get a widget name by Gtk.Buildable.get_name(obj)
body: <p>I'd like to show and hide some windows and logging their names.</p>
  
  <p>But i'm unable to do it, so i printed some interesting facts:</p>
  
  <pre><code>print Gtk.Buildable.get_name(menuitem)
  print menuitem.get_toplevel()
  print Gtk.Buildable.get_name(menuitem.get_toplevel())
  
  --- OUTPUT -----------------------------------------------
  
  Configurazione2_Menuitem
  &lt;Window object at 0x7f81880e7280 (GtkWindow at 0x15b9a40)&gt;
  None
  </code></pre>
  
  <p>So i'm unable to hide the current window. Because this one can't work:</p>
  
  <pre><code>menuitem.get_toplevel().hide() #hide_currentwindow
  </code></pre>