Fix focus issues with fullscreen notification

This is conceptually similar to the release_focus
signal added in 6aa19eb90f and
6f21accfae, but without having to thread the
signal through to TabbedBrowser and back.

Weirdly, doing self.setFocusPolicy(Qt.FocusPolicy.NoFocus) in
FullscreenNotification.__init__ did not help, so let's just set the focus
manually instead.

Fixes #8174.
Fixes #8625.

doc/changelog.asciidoc

@@ -53,6 +53,8 @@ Fixed
   from a `qute://` page to a web page, e.g. when searching on `qute://start`
 - Hopefully proper fix for some web pages jumping to the top when the statusbar
   is hidden. (#8223)
+- Fix for the page header being shown on YouTube after the fullscreen notification was hidden (#8625).
+- Fix for videos losing keyboard focus when the fullscreen notification shows (#8174).
 
 [[v3.5.1]]
 v3.5.1 (2025-06-05)

qutebrowser/browser/webengine/webenginetab.py

@@ -940,6 +940,10 @@ class _WebEnginePermissions(QObject):
                 notif = miscwidgets.FullscreenNotification(self._widget)
                 notif.set_timeout(timeout)
                 notif.show()
+                # Restore keyboard focus to the tab. Setting a NoFocus policy
+                # for FullscreenNotification doesn't seem to work.
+                if self._widget.isVisible():
+                    self._widget.setFocus()
 
     @pyqtSlot(QUrl, 'QWebEnginePage::Feature')
     def _on_feature_permission_requested(self, url, feature):