Fix startup settings window flash

Signed-off-by: Loren Eteval <loren.eteval@proton.me>

Furious/Window/SettingsPage.py

@@ -777,7 +777,8 @@ class SettingsPage(Mixins.QTranslatable, QMainWindow):
         self.addAction(self.findAction)
 
         self.generalSection = _SettingsSection(_('General'))
-        self.tunSection = _SettingsSection('TUN', translatable=False)
+        # Visibility is set before layout adoption; keep the section a child.
+        self.tunSection = _SettingsSection('TUN', translatable=False, parent=self)
         self.connectionSection = _SettingsSection(_('Connection and Interface'))
         self.applicationSection = _SettingsSection(_('Application'))
         self.pluginSettingsTitleLabel = AppQLabel(_('Plugin Settings'))

tests/README.md

@@ -114,7 +114,7 @@ worker. Choose tests by the changed contract rather than by filename alone.
 | [test_main_window_geometry.py](test_main_window_geometry.py) | First-show lifecycle, restored/default/legacy geometry, main/routing window reuse, session-only navigation state, protection of never-shown windows' saved geometry. |
 | [test_dialog_geometry.py](test_dialog_geometry.py) | Dialog show/open/exec preparation, sizing/centering, failure cleanup, specialized message-box geometry and transient destruction. |
 | [test_layout_matrix.py](test_layout_matrix.py) | Navigation and message-box layouts in fresh processes at scale factors 1, 1.25, 1.5, and 2, under both themes. |
-| [test_ui_behavior.py](test_ui_behavior.py) | Translation and editor mappings, settings organization/search/platform gates, stable server/routing moves, real QR rendering/decoding, incremental log filtering/tail behavior, connected-routing change notices, message boxes and connection-error copy/log navigation, shared Home/tray state. |
+| [test_ui_behavior.py](test_ui_behavior.py) | Translation and editor mappings, settings construction visibility/organization/search/platform gates, stable server/routing moves, real QR rendering/decoding, incremental log filtering/tail behavior, connected-routing change notices, message boxes and connection-error copy/log navigation, shared Home/tray state. |
 | [test_qt_interactions.py](test_qt_interactions.py) | Real keyboard/mouse/focus and proxy mapping, scoped shortcuts, sorting/selection, stable subscription deletion confirmations, debounced Home search, Tests-menu selection color, shared settings, batched profile mutation and cancellation. |
 | [test_qr_export_scalability.py](test_qr_export_scalability.py) | Production capture cap, immediate single export, incremental yielding, failure/cancel/close paths, immutable snapshots, window-owned state destruction. |
 | [test_stylesheet_states.py](test_stylesheet_states.py) | Targeted rendering/alpha/geometry assertions for table/list insets, popup corners, clear buttons, focus/disabled states, and stylesheet composition. |

tests/test_ui_behavior.py

@@ -449,6 +449,70 @@ class SettingsPageOrganizationTest(unittest.TestCase):
 
         return page, callbacks
 
+    def testConstructionDoesNotShowTopLevelSettingsWidgets(self):
+        """Never expose a section as a separate window before layout adoption."""
+
+        class ShowObserver(QtCore.QObject):
+            def __init__(self, parent):
+                super().__init__(parent)
+
+                self.shownWindows = []
+
+            def eventFilter(self, watched, event):
+                if (
+                    event.type() == QtCore.QEvent.Type.Show
+                    and isinstance(watched, QWidget)
+                    and watched.isWindow()
+                ):
+                    self.shownWindows.append(type(watched).__name__)
+
+                return False
+
+        cases = (
+            ('Windows', ''),
+            ('Darwin', ''),
+            ('Linux', ''),
+            ('Linux', 'io.github.LorenEteval.Furious'),
+        )
+        app = application()
+
+        for platform, flatpakID in cases:
+            with self.subTest(platform=platform, flatpakID=flatpakID):
+                observer = ShowObserver(app)
+                page = None
+                app.installEventFilter(observer)
+
+                with mock.patch('sys.excepthook') as callbackExceptionHook:
+                    try:
+                        page, _callbacks = self.buildPage(
+                            platform=platform, flatpakID=flatpakID
+                        )
+
+                        self.assertEqual(observer.shownWindows, [])
+                        self.assertFalse(page.isVisible())
+                        self.assertFalse(page.tunSection.isWindow())
+                        self.assertEqual(page.tunSection.isHidden(), bool(flatpakID))
+                        self.assertEqual(
+                            page.tunSection in page._searchSections, not flatpakID
+                        )
+
+                        page.show()
+                        processQtEvents()
+
+                        self.assertTrue(page.isVisible())
+                        self.assertEqual(page.tunSection.isVisible(), not flatpakID)
+                    finally:
+                        app.removeEventFilter(observer)
+
+                        if page is not None:
+                            page.close()
+                            page.deleteLater()
+
+                        observer.deleteLater()
+                        processQtEvents()
+
+                    callbackExceptionHook.assert_not_called()
+
     def testSearchMatchesDescriptionsAndSectionsWithoutApplyingSettings(self):
         with isolatedSettings():
             AppSettings.set('Language', 'EN')