GtkUIManager questions.

["Nils O." Selåsdal <noselasd frisurf no>]

I have a few GtkUIManager questions, first, is there
some nice tutorials/guides anywhere ?
1 With the following:
<ui><popup name="ProjectPopup>
       <menuitem name="Build" action="Build"/>
      <menuitem name="Execute" action="Execute"/>
      <separator/>
      <menuitem name="MoveUp" action="MoveUp"/>
      <menuitem name="MoveDown" action="MoveDown"/>
      <separator/>
      <menuitem name="Remove" action="Remove"/>
  </popup>
</ui>
Only the first separator shows, not the second !

2. What's the <placeholder> for ?

3. Constructing a menubar, how can I replace (and later
   reenable) an entire menu, say I want to replace
   a top "File" menu at a time, and later put it back.
4. Wouldn't a 
GtkActionGroup gtk_ui_manager_get_action_by_name(GtkUIManager *self,
                                             const gchar *name);
  be nice ?