Set the program name to ensure the app icon appears in Running Apps

src/main.py

@@ -19,6 +19,7 @@ class Application(Gtk.Application):
     def __init__(self):
         super().__init__(application_id='com.example.title_bar')
         GLib.set_application_name('Title Bar')
+        GLib.set_prgname('com.example.title_bar')
 
     def do_activate(self):
         window = Gtk.ApplicationWindow(application=self)