Taskbar icon in PyGObject

My vision of the program: the tray icon, the left mouse button icon opens a window with shutdown, restart, etc. buttons.

The new Gnome specification recommends using notifications.

StatusIcon>! (Deprecated since 3.14: using notifications)

Unfortunately I haven't found how the Notify.Notification can appear in the tray. The only one I found was AppIndicator3.Indicator , but its constructor can only use Gtk.Menu, which is not useful.

What classes can I use?