From 1a7da7096bbda17197738061902f4489af234bc0 Mon Sep 17 00:00:00 2001
From: Denis Dzyubenko <denis.dzyubenko@nokia.com>
Date: Tue, 2 Jun 2009 14:59:17 +0200
Subject: Setting a focus on a widget hierarchy which contains both visible and
 invisible widgets could cause a crash.

Also, when there is a widget hierarchy A->B->C and A and C are marked
as visible but B is hidden, when the user gives focus explicitely to
C, we should remember that and respect it when B becomes visible.

Task-number: 254563
Reviewed-by: Thierry Bastian
---
 src/gui/kernel/qwidget.cpp         | 11 ++++++++++-
 tests/auto/qwidget/tst_qwidget.cpp | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 5538c11..d436ffb 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -5674,10 +5674,15 @@ void QWidget::setFocus(Qt::FocusReason reason)
             w = w->isWindow() ? 0 : w->parentWidget();
         }
     } else {
-        while (w) {
+        while (w && w->isVisible()) {
             w->d_func()->focus_child = f;
             w = w->isWindow() ? 0 : w->parentWidget();
         }
+        // a special case, if there is an invisible parent, notify him
+        // about the focus_child widget, so that if it becomes
+        // visible, the focus widget will be respected.
+        if (w)
+            w->d_func()->focus_child = f;
     }
 
 #ifndef QT_NO_GRAPHICSVIEW
@@ -6729,6 +6734,10 @@ void QWidgetPrivate::show_helper()
     if (QApplicationPrivate::hidden_focus_widget == q) {
         QApplicationPrivate::hidden_focus_widget = 0;
         q->setFocus(Qt::OtherFocusReason);
+    } else if (focus_child) {
+        // if we are shown and there is an explicit focus child widget
+        // set, respect it by giving him focus.
+        focus_child->setFocus(Qt::OtherFocusReason);
     }
 
     // Process events when showing a Qt::SplashScreen widget before the event loop
diff --git a/tests/auto/qwidget/tst_qwidget.cpp b/tests/auto/qwidget/tst_qwidget.cpp
index 23ead01..3fad366 100644
--- a/tests/auto/qwidget/tst_qwidget.cpp
+++ b/tests/auto/qwidget/tst_qwidget.cpp
@@ -350,6 +350,9 @@ private slots:
     void updateOnDestroyedSignal();
     void toplevelLineEditFocus();
 
+    void focusWidget_task254563();
+    void focusWidget_mixed_widget_hierarchy();
+
 private:
     bool ensureScreenSize(int width, int height);
     QWidget *testWidget;
@@ -8977,5 +8980,37 @@ void tst_QWidget::toplevelLineEditFocus()
     QCOMPARE(QApplication::focusWidget(), &w);
 }
 
+void tst_QWidget::focusWidget_task254563()
+{
+    //having different visibility for widget is important
+    QWidget top;
+    top.show();
+    QWidget container(&top);
+    QWidget *widget = new QWidget(&container);
+    widget->show();
+
+    widget->setFocus(); //set focus (will set the focus widget up to the toplevel to be 'widget')
+    container.setFocus();
+    delete widget; // will call clearFocus but that doesn't help
+    QVERIFY(top.focusWidget() != widget); //dangling pointer
+}
+
+void tst_QWidget::focusWidget_mixed_widget_hierarchy()
+{
+    QWidget top;
+    top.show();
+    QWidget notvisible(&top);
+    QWidget *visible = new QWidget(&notvisible);
+    visible->show();
+
+    visible->setFocus();
+    notvisible.setFocus();
+    notvisible.show();
+    QCOMPARE(top.focusWidget(), visible);
+    QCOMPARE(notvisible.focusWidget(), visible);
+    QCOMPARE(visible->focusWidget(), visible);
+}
+
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"
-- 
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