"losing" widget names

[John Breen <john linuxwa com au>]

Ok, I got moving widgets from one container to another to work.  The
gtk_widget_reparent() worked fine.

Now, I want to ONLY create the new window (and widgets) if they don't
already exist.  I've tried this:

%<-------------------------------------------------------------------------------

void
on_inventory_add_items_activate        (GtkMenuItem     *menuitem,
                                        gpointer         user_data)
{
	GtkWidget *mainwindow, *newparent, *inventorywindow, *vbox;
	
	/* if the inventory stuff is not visible, make it so. */
	mainwindow = lookup_widget(GTK_WIDGET(menuitem), "main_window");
	if(!lookup_widget(mainwindow, "inventory_frame"))
	{
		newparent = lookup_widget(mainwindow, "vbox1");
		inventorywindow = create_inventory_window();
		vbox = lookup_widget(inventorywindow, "inventory_frame");
		gtk_widget_reparent(vbox, newparent);

		gtk_widget_show_all(vbox); 
	
		gtk_widget_destroy(inventorywindow);
	}

}

%<-----------------------------------------------------------------------------

But clicking the menu option twice simply adds two copies of
inventory_frame to vbox1.  It seems that inventory_frame isn't
recognised as being a part of mainwindow.

Any ideas?

TIA

John Breen