Delay saving settings until closing the app

This radically improves the performance of resizing the window, as it no
longer has to save the three updated values on every resize signal.
The volume slider is also smoother now.

cozy/application_settings.py

@@ -9,6 +9,7 @@ class ApplicationSettings(EventSender):
 
     def __init__(self):
         super().__init__()
+        self._settings.delay()
         self._connect()
 
     def _connect(self):

cozy/ui/main_view.py

@@ -31,6 +31,7 @@ class CozyUI(EventSender, metaclass=Singleton):
     application_settings = inject.attr(ApplicationSettings)
     _importer: Importer = inject.attr(Importer)
     _settings: SettingsModel = inject.attr(SettingsModel)
+    _gio_settings: Gio.Settings = inject.attr(Gio.Settings)
     _files: Files = inject.attr(Files)
     _player: Player = inject.attr(Player)
     _storages_view_model: StoragesViewModel = inject.attr(StoragesViewModel)
@@ -67,8 +68,6 @@ def __init_window(self):
         self.window.set_application(self.app)
 
         self.window.connect("close-request", self.on_close)
-        self.window.connect("notify::default-width", self._on_window_size_allocate)
-        self.window.connect("notify::default-height", self._on_window_size_allocate)
 
         self._drop_target = Gtk.DropTarget()
         self._drop_target.set_gtypes([Gdk.FileList])
@@ -228,12 +227,16 @@ def on_close(self, widget, data=None):
         log.info("Closing.")
         self.fs_monitor.close()
 
+        self._save_window_size()
+
         self._player.destroy()
 
         close_db()
 
         report.close()
 
+        log.info("Saving settings.")
+        self._gio_settings.apply()
         log.info("Closing app.")
         self.app.quit()
         log.info("App closed.")
@@ -254,7 +257,7 @@ def _restore_window_size(self):
         else:
             self.window.unmaximize()
 
-    def _on_window_size_allocate(self, *_):
+    def _save_window_size(self, *_):
         width, height = self.window.get_default_size()
         self.application_settings.window_width = width
         self.application_settings.window_height = height