[gtkmm] About constructor's parameters using libglademm

["courier qiu" <qiu_lb yeah net>]

When using libglademm to load "some_ui.glade" file:
(1) I don't know why the signature of Class's Constructor should be like the example below. 
(2) i know cobject will be passed to Gtk::Dialog, but what is passed to cobject and refGlade? 
(3) and when these happen?  

/////////////////////////////////////////////////////////////////////////////////////////
class DerivedDialog : public Gtk::Dialog
{
public:
  DerivedDialog(BaseObjectType* cobject, const Glib::RefPtr<Gnome::Glade::Xml>& refGlade);
  ...
};
	
int main (int argc, char **argv)
{
  ...
  
  lib::RefPtr<Gnome::Glade::Xml> refXml = Gnome::Glade::Xml::create("some_ui.glade");
    
  DerivedDialog* pDialog = 0;
  refXml->get_widget_derived("DialogBasic", pDialog);   
    
  ...
  
}
//////////////////////////////////////////////////////////////////////////////////////　　　　　　　　
can someone tell me? thanks very much!
 				

　　　　　　　　courier qiu
　　　　　　　　qiu_lb yeah net
　　　　　　　　　　2004-09-22