Release the main window's native window when it is closed

src/vorta/views/main_window.py

@@ -3,7 +3,7 @@
 from pathlib import Path
 
 from PyQt6 import QtCore, uic
-from PyQt6.QtCore import QPoint, Qt
+from PyQt6.QtCore import QPoint, Qt, QTimer
 from PyQt6.QtCore import pyqtSignal as Signal
 from PyQt6.QtGui import QFontMetrics, QKeySequence, QShortcut
 from PyQt6.QtWidgets import (
@@ -380,3 +380,11 @@ def closeEvent(self, event):
             elif not SettingsModel.get(key="disable_background_state").value:
                 self.app.quit()
         event.accept()
+        # Closing only hides the window: Qt keeps the native window and its backing store
+        # (~28 MB on a Retina display) alive while Vorta sits in the tray. Release them once
+        # the close has gone through (Qt hides the widget after this handler returns).
+        QTimer.singleShot(0, self._release_native_window)
+
+    def _release_native_window(self):
+        if not self.isVisible():
+            self.destroy()  # show() creates the native window again

tests/unit/test_main_window.py

@@ -0,0 +1,35 @@
+import pytest
+
+
+def test_close_releases_native_window(qapp, qtbot, monkeypatch):
+    """
+    Closing the main window must release its native window (and with it the backing store),
+    and showing it again must work as before.
+    """
+    main = qapp.main_window
+    was_visible = main.isVisible()
+    # Take the tray path in closeEvent(), also where no tray exists (headless CI).
+    monkeypatch.setattr('vorta.views.main_window.is_system_tray_available', lambda: True)
+
+    def shown():
+        return main.isVisible() and main.windowHandle() is not None
+
+    def released():
+        return not main.isVisible() and main.windowHandle() is None
+
+    qapp.open_main_window_action()
+    qtbot.waitUntil(shown, **pytest._wait_defaults)
+
+    main.close()
+    qtbot.waitUntil(released, **pytest._wait_defaults)
+
+    qapp.open_main_window_action()
+    qtbot.waitUntil(shown, **pytest._wait_defaults)
+
+    main.close()
+    qtbot.waitUntil(released, **pytest._wait_defaults)
+
+    # Leave the window as the other tests expect it.
+    if was_visible:
+        qapp.open_main_window_action()
+        qtbot.waitUntil(shown, **pytest._wait_defaults)