How can I display the buttons in a dialog's action area vertically?

[Paul Santa Maria <paulsm1021 yahoo com>]

Hi -

I have a pop-up window (a GtkDialog) that presents a list of about a dozen
choices.  I want to display these choices vertically.  The action area seems to
be an HBox.  Any suggestions?

Here's the basic code:

  m_dialog1 = gtk_dialog_new ();
  gtk_window_set_title (GTK_WINDOW (m_dialog1), title);
  gtk_window_set_type_hint (GTK_WINDOW (m_dialog1),
    GDK_WINDOW_TYPE_HINT_DIALOG);
  ...
  GtkWidget *dialog_action_area1 = GTK_DIALOG (m_dialog1)->action_area;
  gtk_widget_show (dialog_action_area1);
  gtk_button_box_set_layout (GTK_BUTTON_BOX (dialog_action_area1), 
    GTK_BUTTONBOX_END);

  // Add custom pushbuttons into action area
  GtkWidget *button1 = gtk_button_new_with_mnemonic (_("1) Moe"));
  gtk_widget_show (button1);
  gtk_dialog_add_action_widget (GTK_DIALOG (m_dialog1), button1, 1);
  ...
  <= WE'RE DOING A BUNCH OF "ADD_ACTION_WIDGET'S" TO WHAT APPEARS TO
     BE AN HBOX.

     IS THERE ANY WAY TO CHANGE THE ACTION AREA INTO A VBOX INSTEAD?

     IF I CREATED AN INTERPOSED MY OWN VBOX, COULD I STILL 
     DO "ADD_ACTION_WIDGET" INTO IT?