add app groups

examples/app_library/grid_item/imp.rs

@@ -0,0 +1,34 @@
+use gtk::glib;
+use gtk::prelude::*;
+use gtk::subclass::prelude::*;
+use gtk4 as gtk;
+
+use gtk::CompositeTemplate;
+
+#[derive(Debug, Default, CompositeTemplate)]
+#[template(file = "grid_item.ui")]
+pub struct GridItem {
+    #[template_child]
+    pub name: TemplateChild<gtk::Label>,
+    #[template_child]
+    pub image: TemplateChild<gtk::Image>,
+}
+
+#[glib::object_subclass]
+impl ObjectSubclass for GridItem {
+    const NAME: &'static str = "GridItem";
+    type Type = super::GridItem;
+    type ParentType = gtk::Box;
+
+    fn class_init(klass: &mut Self::Class) {
+        Self::bind_template(klass);
+    }
+
+    fn instance_init(obj: &glib::subclass::InitializingObject<Self>) {
+        obj.init_template();
+    }
+}
+
+impl ObjectImpl for GridItem {}
+impl WidgetImpl for GridItem {}
+impl BoxImpl for GridItem {}