Set up an application quit action group

This ties together a menu item, closing the main window, and Ctrl-Q into
the same action, which is to quit the application.

fitnesstrax/app/src/app_window.rs

@@ -56,6 +56,9 @@ impl AppWindow {
             .width_request(800)
             .height_request(746)
             .build();
+        window.connect_destroy(|s| {
+            let _ = gtk::prelude::WidgetExt::activate_action(s, "app.quit", None);
+        });
 
         let stylesheet = String::from_utf8(
             resources_lookup_data(
@@ -83,10 +86,22 @@ impl AppWindow {
 
         let initial_view = View::Placeholder(PlaceholderView::default().upcast());
 
+        let header_bar = adw::HeaderBar::new();
+
+        let main_menu = gio::Menu::new();
+        main_menu.append(Some("Quit"), Some("app.quit"));
+        let main_menu_button = gtk::MenuButton::builder()
+            .icon_name("open-menu")
+            .direction(gtk::ArrowType::Down)
+            .halign(gtk::Align::End)
+            .menu_model(&main_menu)
+            .build();
+        header_bar.pack_end(&main_menu_button);
+
         layout.append(&initial_view.widget());
 
         let nav_layout = gtk::Box::new(gtk::Orientation::Vertical, 0);
-        nav_layout.append(&adw::HeaderBar::new());
+        nav_layout.append(&header_bar);
         nav_layout.append(&layout);
         navigation.push(
             &adw::NavigationPage::builder()

fitnesstrax/app/src/main.rs

@@ -25,6 +25,8 @@ mod views;
 
 use adw::prelude::*;
 use app_window::AppWindow;
+use components::ActionGroup;
+use gio::{Action, ActionEntry};
 use std::{env, path::PathBuf};
 
 const APP_ID_DEV: &str = "com.luminescent-dreams.fitnesstrax.dev";
@@ -65,6 +67,14 @@ fn main() {
         let icon_theme = gtk::IconTheme::for_display(&gdk::Display::default().unwrap());
         icon_theme.add_resource_path(&(RESOURCE_BASE_PATH.to_owned() + "/icons/scalable/actions"));
 
+        let app_close_action = ActionEntry::builder("quit")
+            .activate(|app: &adw::Application, _, _| {
+                app.quit();
+            })
+            .build();
+        adw_app.add_action_entries([app_close_action]);
+        adw_app.set_accels_for_action("app.quit", &["<Ctrl>Q"]);
+
         AppWindow::new(app_id, RESOURCE_BASE_PATH, adw_app, ft_app.clone());
     });