Allow wheel events on focused boxes when window is inactive

dikte/settings_ui.py

@@ -207,7 +207,9 @@ class WheelGuard(QObject):
     """
 
     def eventFilter(self, box, event):
-        if event.type() == QEvent.Type.Wheel and not box.hasFocus():
+        win = box.window()
+        focused = box.hasFocus() or (win is not None and win.focusWidget() is box)
+        if event.type() == QEvent.Type.Wheel and not focused:
             # Refused rather than swallowed. An unaccepted wheel event carries
             # on up the parents to the scroll area, so the page still moves.
             event.ignore()

tests/test_ui.py

@@ -223,6 +223,17 @@ class Settings(DikteTest):
         QApplication.sendEvent(box, self.wheel())
         self.assertNotEqual(box.currentIndex(), before)
 
+    def test_the_wheel_is_refused_when_another_widget_has_focus(self):
+        window = self.window(cfg.Config())
+        box = window.ui_language
+        other = window.corner
+        other.setFocus()
+        before = box.currentIndex()
+        rolled = self.wheel()
+        QApplication.sendEvent(box, rolled)
+        self.assertEqual(box.currentIndex(), before)
+        self.assertFalse(rolled.isAccepted())
+
     def test_a_wrapped_label_keeps_the_room_its_lines_need(self):
         # The program path shares a row with a button, and a row is measured
         # before its width is known: the label has to claim the second line back