correct menu_bar.ui

hello_world.cpp

@@ -6,15 +6,15 @@
 #include <iostream>
 
 namespace learn_gtkmm4 {
-    HelloWorld::HelloWorld() : m_button("Hello world!") {
+    HelloWorld::HelloWorld(const Glib::RefPtr<Gio::Menu>& menuModel) :
+            m_VBox(Gtk::Orientation::VERTICAL), m_menu_bar(menuModel), m_button("Hello world!") {
         set_title("Hello world!");
-        set_default_size(720, 1280);
+        set_default_size(1280, 720);
-        add_action("Open");
-        add_action("Quit");
-        set_show_menubar();
         m_button.set_margin(10);
         m_button.signal_clicked().connect(sigc::mem_fun(*this, &HelloWorld::on_button_clicked));
-        set_child(m_button);
+        m_VBox.append(m_menu_bar);
+        m_VBox.append(m_button);
+        set_child(m_VBox);
     }
 
     void HelloWorld::on_button_clicked() {

hello_world.hpp

@@ -9,18 +9,21 @@
 #include <gtkmm/glarea.h>
 #include <gtkmm/box.h>
 #include <gtkmm/applicationwindow.h>
+#include <gtkmm/popovermenubar.h>
+#include <gtkmm/popovermenu.h>
 
 namespace learn_gtkmm4 {
 
     class HelloWorld : public Gtk::ApplicationWindow {
     public:
-        HelloWorld();
+        explicit HelloWorld(const Glib::RefPtr<Gio::Menu>& menuModel);
         ~HelloWorld() override = default;
 
     protected:
         void on_button_clicked();
 
         Gtk::Box m_VBox;
+        Gtk::PopoverMenuBar m_menu_bar;
         Gtk::Button m_button;
         Gtk::GLArea gl_area;
     };

main.cpp

@@ -1,7 +1,24 @@
 #include "hello_world.hpp"
 #include <gtkmm/application.h>
+#include <gtkmm/builder.h>
+#include <iostream>
+#include <memory>
 
 int main(int argc, char *argv[]) {
     auto app = Gtk::Application::create("org.gtkmm.example");
-    return app->make_window_and_run<learn_gtkmm4::HelloWorld>(argc, argv);
+
+    const auto menu_model = []() -> Glib::RefPtr<Gio::Menu> {
+        try {
+            const auto builder = Gtk::Builder::create_from_file("menu_bar.ui");
+            return std::dynamic_pointer_cast<Gio::Menu>(builder->get_object("menu"));
+        } catch (const std::exception &e) {
+            std::cerr << e.what() << '\n';
+            return nullptr;
+        }
+    }();
+    if (menu_model == nullptr) {
+        std::cerr << "Menu model object is null. Down-cast failed.\n";
+        return EXIT_FAILURE;
+    }
+    return app->make_window_and_run<learn_gtkmm4::HelloWorld>(argc, argv, menu_model);
 }

menu_bar.ui

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <requires lib="gio" version="2.0"/>
+  <menu id="menu">
+    <submenu id="file_submenu">
+      <attribute name="label" translatable="yes" context="&quot;Files&quot; menu used here">Fichiers</attribute>
+      <section>
+        <item>
+          <attribute name="action">file.new</attribute>
+          <attribute name="icon">document-new</attribute>
+          <attribute name="label" translatable="yes" context="It means New File in french">Nouveau fichier</attribute>
+        </item>
+        <item>
+          <attribute name="action">file.open</attribute>
+          <attribute name="icon">document-open</attribute>
+          <attribute name="label" translatable="yes" context="It means Open in french">Ouvrir</attribute>
+        </item>
+        <item>
+          <attribute name="action">file.save</attribute>
+          <attribute name="icon">document-save</attribute>
+          <attribute name="label" translatable="yes" context="It means Save">Enregistrer</attribute>
+        </item>
+        <item>
+          <attribute name="action">file.save_as</attribute>
+          <attribute name="icon">document-save-as</attribute>
+          <attribute name="label" translatable="yes" context="It means Save">Enregistrer sous</attribute>
+        </item>
+      </section>
+      <section>
+        <item>
+          <attribute name="action">file.quit</attribute>
+          <attribute name="icon">application-exit</attribute>
+          <attribute name="label" translatable="yes" context="It means Quit">Quitter</attribute>
+        </item>
+      </section>
+    </submenu>
+    <submenu id="edit_submenu">
+      <attribute name="label" translatable="yes" context="It means Edit">Éditer</attribute>
+      <section>
+        <item>
+          <attribute name="action">edit.copy</attribute>
+          <attribute name="icon">edit-copy</attribute>
+          <attribute name="label" translatable="yes">Copier</attribute>
+        </item>
+        <item>
+          <attribute name="action">edit.cut</attribute>
+          <attribute name="icon">edit-cut</attribute>
+          <attribute name="label" translatable="yes">Couper</attribute>
+        </item>
+        <item>
+          <attribute name="action">edit.paste</attribute>
+          <attribute name="icon">edit-paste</attribute>
+          <attribute name="label" translatable="yes">Coller</attribute>
+        </item>
+      </section>
+    </submenu>
+  </menu>
+</interface>