Fix QAccessibleWidget::focusChild() to return focused descendant

This method should not ignore accessibility objects without
corresponding widget. The widget may have parts with their own
QAccessibilityInterface and these can be also focused.

VoiceOver ignores them if they are not returned by focusChild().

QAccessibleTabBar::focusChild() has been implemented to demonstrate
the concept and make tab titles of QTabBar readable by VoiceOver.

Task-number: QTBUG-78284
Change-Id: Id7c62d86154bbd5d47d6bbee8cb7d05268c2e151
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 8 insertions, 4 deletions

diff --git a/src/widgets/accessible/qaccessiblewidget.cpp b/src/widgets/accessible/qaccessiblewidget.cpp
index 27e6b09dc7..3ab66c4ce4 100644
--- a/src/widgets/accessible/qaccessiblewidget.cpp
+++ b/src/widgets/accessible/qaccessiblewidget.cpp
@@ -374,11 +374,15 @@ QAccessibleInterface *QAccessibleWidget::focusChild() const
 
     QWidget *fw = widget()->focusWidget();
     if (!fw)
-        return 0;
+        return nullptr;
 
-    if (isAncestor(widget(), fw) || fw == widget())
-        return QAccessible::queryAccessibleInterface(fw);
-    return 0;
+    if (isAncestor(widget(), fw)) {
+        QAccessibleInterface *iface = QAccessible::queryAccessibleInterface(fw);
+        if (!iface || iface == this || !iface->focusChild())
+            return iface;
+        return iface->focusChild();
+    }
+    return nullptr;
 }
 
 /*! \reimp */