[gtkmm] MessageDialog example has error

["B D Bird" <aviary tree ntlworld com>]

Hi,

Learning gtkmm, I tried out the messagedialog example in Chapter 13.

Small Extract:

void ExampleWindow::on_button_question_clicked()
{
  Gtk::MessageDialog dialog(*this, "This is a QUESTION MessageDialog",
Gtk::MESSAGE_QUESTION, (Gtk::ButtonsType)(Gtk::BUTTONS_OK |
Gtk::BUTTONS_CANCEL));

It turns out you cannot OR two Buttons Types together.  To get what is
obviously required you have to use BUTTONS_OK_CANCEL.

Regards,

Barry Bird