[Ada][GtkAda] Problème avec Notebook.Next_Page

Source ada : 

-------------------------------------------------------------------------------
   -- Create device page : (add and remove device(s)                            --
   -------------------------------------------------------------------------------   
   procedure Create_Device_Page(Notebook      : access Gtk_Notebook_Record'Class;
            Gtk_Interface : in Gtk_Interface_Pointer;
            Device_Num    : in positive) is
      
      Vbox : Gtk_Vbox;
      
      Hbox : Gtk_Hbox;
      
      Page_Num : constant Gint := Get_N_Pages(Notebook);      
      
      Label    : Gtk_Label;
      
      Input_Label  : Gtk_Label;
      Output_Label : Gtk_Label;
      
      Input_List : constant Devices_List_Access := Inputs_List;
      Output_List : constant Devices_List_Access := Outputs_List;
   begin
      
      Put_Line("Create page num : " & Gint'Image(Page_Num));
      
      Gtk_New_Vbox (Vbox, False, 0);
      Gtk_New(Label, "Device Id :" & Gint'Image(Page_Num+1));                  
      
      if Gtk_Interface.Gm_Application.Devices_Info(Device_Num) = null then
    Gtk_Interface.Gm_Application.Devices_Info(Device_Num) := new Device_Record;
      end if;
      
      Gtk_Interface.Devices_Pages(Positive(Page_Num+1)) := new Device_Page_Record;
            
      Gtk.Combo_Box_text.Gtk_New(Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Input_Device);
      --
      for Input in Input_List'Range loop
    if Input_List(Input).Name /= null then
       Gtk.Combo_Box_text.Append_Text
         (Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Input_Device,
          Input_List(Input).Name.all);
    end if;
      end loop;
      if Inputs_Devices(Device_Num) /= (-1) then
    Gtk.Combo_Box_text.Set_Active
      (Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Input_Device,
       Gint(Inputs_Devices(Device_Num)));
      end if;
       
      Devices_User_Callback.Connect
   (Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Input_Device,
    "changed",
    Devices_User_Callback.To_Marshaller(Set_Input_Device'Access),
    Gtk_Interface);
                       
      Gtk.Combo_Box_text.Gtk_New(Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Output_Device);
      --
      for Output in Output_List'Range loop
    if Output_List(Output).Name /= null then
       Gtk.Combo_Box_Text.Append_Text
         (Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Output_Device,
          Output_List(Output).Name.all);
    end if;
      end loop;
      if Outputs_Devices(Device_Num) /= (-1) then
    Gtk.Combo_Box_text.Set_Active
      (Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Output_Device,
       Gint(Outputs_Devices(Device_Num)));
      end if;

      Devices_User_Callback.Connect
   (Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Output_Device,
    "changed",
    Devices_User_Callback.To_Marshaller(Set_Output_Device'Access),
    Gtk_Interface);

      
      
      
      Gtk_New(Input_Label, "Input  : ");
      Gtk_New(Output_Label, "Output : ");
      
      Gtk_New_Hbox(Hbox, False, 0);
      Pack_Start(Hbox, Input_Label);      
      Pack_Start(Hbox, Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Input_Device);
      
      Pack_Start(Vbox, Hbox);
      
      Gtk_New_Hbox(Hbox, False, 0);
      Pack_Start(Hbox, Output_Label);      
      Pack_Start(Hbox, Gtk_Interface.Devices_Pages(Positive(Page_Num+1)).Output_Device);
      
      Pack_Start(Vbox, Hbox);
      
      Append_Page (Notebook, Vbox, Label);
      Show_All(Notebook);
      
      --  for I in Gint(Gtk_Interface.Cur_Page) .. Page_Num + 1 loop
      --     Next_Page(Notebook);

      --  end loop;    
      
      Gtk_Interface.Cur_Page := Integer(Get_N_Pages(Notebook)-1);
      Put_Line("Cur_Page : " & Integer'Image(Gtk_Interface.Cur_Page));
   end Create_Device_Page;