[gtkmm-documentation] Menu examples: Use the templated Gtk::Builder::get_object<>()

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 3c63b2fd0d4895be81beac9f1ca1e17305c28b53
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Jul 11 19:02:49 2022 +0200

    Menu examples: Use the templated Gtk::Builder::get_object<>()
    
    * examples/book/menus/main_menu/exampleapplication.cc:
    * examples/book/menus/popup/examplewindow.cc:
    * examples/book/menus_and_toolbars/examplewindow.cc:
    Use m_refBuilder->get_object<Gio::Menu>("menu"). That's what
    the tutorial describes.

 examples/book/menus/main_menu/exampleapplication.cc | 4 ++--
 examples/book/menus/popup/examplewindow.cc          | 5 +----
 examples/book/menus_and_toolbars/examplewindow.cc   | 5 ++---
 3 files changed, 5 insertions(+), 9 deletions(-)
---
diff --git a/examples/book/menus/main_menu/exampleapplication.cc 
b/examples/book/menus/main_menu/exampleapplication.cc
index 47d1cbf..7210e2c 100644
--- a/examples/book/menus/main_menu/exampleapplication.cc
+++ b/examples/book/menus/main_menu/exampleapplication.cc
@@ -57,6 +57,7 @@ void ExampleApplication::on_startup()
   set_accel_for_action("app.quit", "<Primary>q");
   set_accel_for_action("win.copy", "<Primary>c");
   set_accel_for_action("win.paste", "<Primary>v");
+
   m_refBuilder = Gtk::Builder::create();
 
   //Layout the actions in a menubar and a menu:
@@ -170,8 +171,7 @@ void ExampleApplication::on_startup()
   }
 
   //Get the menubar and the app menu, and add them to the application:
-  auto object = m_refBuilder->get_object("menu-example");
-  auto gmenu = std::dynamic_pointer_cast<Gio::Menu>(object);
+  auto gmenu = m_refBuilder->get_object<Gio::Menu>("menu-example");
   if (!gmenu)
   {
     g_warning("GMenu not found");
diff --git a/examples/book/menus/popup/examplewindow.cc b/examples/book/menus/popup/examplewindow.cc
index 3a07e7a..5b0f2bf 100644
--- a/examples/book/menus/popup/examplewindow.cc
+++ b/examples/book/menus/popup/examplewindow.cc
@@ -92,10 +92,7 @@ ExampleWindow::ExampleWindow(const Glib::RefPtr<Gtk::Application>& app)
   }
 
   //Get the menu:
-  auto object =
-    m_refBuilder->get_object("menu-examplepopup");
-  auto gmenu =
-    std::dynamic_pointer_cast<Gio::Menu>(object);
+  auto gmenu = m_refBuilder->get_object<Gio::Menu>("menu-examplepopup");
   if(!gmenu)
     g_warning("GMenu not found");
 
diff --git a/examples/book/menus_and_toolbars/examplewindow.cc 
b/examples/book/menus_and_toolbars/examplewindow.cc
index da0cc21..5367b22 100644
--- a/examples/book/menus_and_toolbars/examplewindow.cc
+++ b/examples/book/menus_and_toolbars/examplewindow.cc
@@ -53,7 +53,7 @@ ExampleWindow::ExampleWindow(const Glib::RefPtr<Gtk::Application>& app)
   m_refBuilder = Gtk::Builder::create();
 
   //Layout the actions in a menubar and toolbar:
-  const char* ui_info =
+  const Glib::ustring ui_info =
     "<interface>"
     "  <menu id='menubar'>"
     "    <submenu>"
@@ -118,8 +118,7 @@ ExampleWindow::ExampleWindow(const Glib::RefPtr<Gtk::Application>& app)
   }
 
   //Get the menubar:
-  auto object = m_refBuilder->get_object("menubar");
-  auto gmenu = std::dynamic_pointer_cast<Gio::Menu>(object);
+  auto gmenu = m_refBuilder->get_object<Gio::Menu>("menubar");
   if (!gmenu)
     g_warning("GMenu not found");
   else