Table of Contents
Dialogs are used as secondary windows, to provide specific information or to
ask questions. Gtk::Dialog windows contain a few pre-packed
widgets to ensure consistency, and a run() method which
blocks until the user dismisses the dialog.
There are several derived Dialog classes which you might
find useful. Gtk::MessageDialog is used for most simple
notifications. But at other times you might need to derive your own dialog
class to provide more complex functionality.
To pack widgets into a custom dialog, you should pack them into the
Gtk::Box, available via
get_content_area(). To just add a Button
to the bottom of the Dialog, you could use the
add_button() method.
The run() method returns an int. This
may be a value from the Gtk::ResponseType if the user
closed the dialog by clicking a standard button, or it could be the custom
response value that you specified when using add_button().
MessageDialog is a convenience class, used to create
simple, standard message dialogs, with a message, an icon, and buttons for user
response. You can specify the type of message and the text in the constructor,
as well as specifying standard buttons via the
Gtk::ButtonsType enum.
File: examplewindow.h (For use with gtkmm 3, not gtkmm 2)
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H
#include <gtkmm.h>
class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  virtual ~ExampleWindow();
protected:
  //Signal handlers:
  void on_button_info_clicked();
  void on_button_question_clicked();
  //Child widgets:
  Gtk::ButtonBox m_ButtonBox;
  Gtk::Button m_Button_Info, m_Button_Question;
};
#endif //GTKMM_EXAMPLEWINDOW_H
File: main.cc (For use with gtkmm 3, not gtkmm 2)
#include "examplewindow.h"
#include <gtkmm/application.h>
int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create(argc, argv, "org.gtkmm.example");
  ExampleWindow window;
  //Shows the window and returns when it is closed.
  return app->run(window);
}
File: examplewindow.cc (For use with gtkmm 3, not gtkmm 2)
#include "examplewindow.h"
#include <gtkmm/messagedialog.h>
#include <iostream>
ExampleWindow::ExampleWindow()
: m_ButtonBox(Gtk::ORIENTATION_VERTICAL),
  m_Button_Info("Show Info MessageDialog"),
  m_Button_Question("Show Question MessageDialog")
{
  set_title("Gtk::MessageDialog example");
  add(m_ButtonBox);
  m_ButtonBox.pack_start(m_Button_Info);
  m_Button_Info.signal_clicked().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_button_info_clicked) );
  m_ButtonBox.pack_start(m_Button_Question);
  m_Button_Question.signal_clicked().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_button_question_clicked) );
  show_all_children();
}
ExampleWindow::~ExampleWindow()
{
}
void ExampleWindow::on_button_info_clicked()
{
  Gtk::MessageDialog dialog(*this, "This is an INFO MessageDialog");
  dialog.set_secondary_text(
          "And this is the secondary text that explains things.");
  dialog.run();
}
void ExampleWindow::on_button_question_clicked()
{
  Gtk::MessageDialog dialog(*this, "This is a QUESTION MessageDialog",
          false /* use_markup */, Gtk::MESSAGE_QUESTION,
          Gtk::BUTTONS_OK_CANCEL);
  dialog.set_secondary_text(
          "And this is the secondary text that explains things.");
  int result = dialog.run();
  //Handle the response:
  switch(result)
  {
    case(Gtk::RESPONSE_OK):
    {
      std::cout << "OK clicked." << std::endl;
      break;
    }
    case(Gtk::RESPONSE_CANCEL):
    {
      std::cout << "Cancel clicked." << std::endl;
      break;
    }
    default:
    {
      std::cout << "Unexpected button clicked." << std::endl;
      break;
    }
  }
}