+end
+
+# An element of an application that is notified of the application life cycle
+#
+# Most users of _app.nit_ need only to implement `on_create` to setup the application.
+#
+# On mobile devices, the application can be stopped a anytime when another application takes the foreground.
+# Implement the callbacks `on_save_state` and `on_load_state` to keep the state of the application between execution,
+# for an illusion of continuous execution.
+abstract class AppComponent
+
+ # The application is being created
+ #
+ # You should build the UI at this time.
+ fun on_create do end