destroying widgets on C++

[Germano Leichsenring <germano s3ws6 seg kobe-u ac jp>]

I have a class which have a window in it; I want the class to be destroyed
when the widget is destroyed, and the widget be destroyed when the class is
destroyed. I've been trying it for a while, but can't find a solution that
works. Has anybody done that? 

myclass::myclass()
{
destroy_handler = 
    gtk_signal_connect(GTK_OBJECT(toplevel_window), "destroy", 
		       GTK_SIGNAL_FUNC(myclass_quit_CB), 
		       (void*)this);
}
myclass::~myclass()
{
  gtk_signal_disconnect(GTK_OBJECT(toplevel_window),destroy_handler);
  if(GTK_IS_WIDGET(toplevel_window))
   gtk_widget_destroy(toplevel_window);
}

myclass_quit_CB(GtkWidget *widget2, 
		    myclass* data, 
		    GtkWidget* widget)
{
  delete data;
}

the problem on this is: 
- if I destroy the class, the widget is destroyed;
- but if I destroy the widget, i'm destroying the widget 2 times.