From a6e5ccbe223c5a606e15556e8708e863442d9f72 Mon Sep 17 00:00:00 2001
From: David Faure <faure@kde.org>
Date: Wed, 28 Nov 2012 14:00:45 +0100
Subject: [PATCH] QMdi: Don't emit subWindowActivated during StyleChange
 handling.

The handling of StyleChange de-maximizes the child window temporarily,
which was emitting subWindowActivated.
This would crash lokalize, because deactivating a window means deleting
the widgets associated with it, and style-change handling is done in
QApplication by looping over QApplication::allWidgets, which would then
contain dangling pointers.

Full valgrind log at https://bugs.kde.org/show_bug.cgi?id=271494#c7

Change-Id: Ifb24032cde2cd470dcae7cd553ec5ab45a919dd6
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
---
 src/widgets/widgets/qmdisubwindow.cpp         |  8 ++++-
 .../qmdisubwindow/tst_qmdisubwindow.cpp       | 31 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/widgets/widgets/qmdisubwindow.cpp b/src/widgets/widgets/qmdisubwindow.cpp
index 4259f750971..b38dea074fd 100644
--- a/src/widgets/widgets/qmdisubwindow.cpp
+++ b/src/widgets/widgets/qmdisubwindow.cpp
@@ -164,6 +164,7 @@
 #include <private/qmacstyle_mac_p.h>
 #endif
 #include <QMdiArea>
+#include <QScopedValueRollback>
 
 QT_BEGIN_NAMESPACE
 
@@ -2789,6 +2790,10 @@ bool QMdiSubWindow::event(QEvent *event)
         bool wasShaded = isShaded();
         bool wasMinimized = isMinimized();
         bool wasMaximized = isMaximized();
+        // Don't emit subWindowActivated, the app doesn't have to know about our hacks
+        const QScopedValueRollback<bool> activationEnabledSaver(d->activationEnabled);
+        d->activationEnabled = false;
+
         ensurePolished();
         setContentsMargins(0, 0, 0, 0);
         if (wasMinimized || wasMaximized || wasShaded)
@@ -3008,7 +3013,8 @@ void QMdiSubWindow::changeEvent(QEvent *changeEvent)
 
     if (d->isActive)
         d->ensureWindowState(Qt::WindowActive);
-    emit windowStateChanged(oldState, windowState());
+    if (d->activationEnabled)
+        emit windowStateChanged(oldState, windowState());
 }
 
 /*!
diff --git a/tests/auto/widgets/widgets/qmdisubwindow/tst_qmdisubwindow.cpp b/tests/auto/widgets/widgets/qmdisubwindow/tst_qmdisubwindow.cpp
index 2163426cacb..477bab8a37c 100644
--- a/tests/auto/widgets/widgets/qmdisubwindow/tst_qmdisubwindow.cpp
+++ b/tests/auto/widgets/widgets/qmdisubwindow/tst_qmdisubwindow.cpp
@@ -154,6 +154,7 @@ Q_DECLARE_METATYPE(Qt::WindowState);
 Q_DECLARE_METATYPE(Qt::WindowStates);
 Q_DECLARE_METATYPE(Qt::WindowType);
 Q_DECLARE_METATYPE(Qt::WindowFlags);
+Q_DECLARE_METATYPE(QMdiSubWindow*);
 
 class tst_QMdiSubWindow : public QObject
 {
@@ -204,6 +205,7 @@ private slots:
     void task_182852();
     void task_233197();
     void task_226929();
+    void styleChange();
 };
 
 void tst_QMdiSubWindow::initTestCase()
@@ -2018,6 +2020,35 @@ void tst_QMdiSubWindow::task_226929()
     QVERIFY(sub1->isMaximized());
 }
 
+void tst_QMdiSubWindow::styleChange()
+{
+    QMdiArea mdiArea;
+    mdiArea.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&mdiArea));
+
+    QMdiSubWindow *sub1 = mdiArea.addSubWindow(new QTextEdit);
+    sub1->showMaximized();
+
+    QMdiSubWindow *sub2 = mdiArea.addSubWindow(new QTextEdit);
+    sub2->showMinimized();
+
+    mdiArea.setActiveSubWindow(sub1);
+
+    QTest::qWait(100);
+
+    qRegisterMetaType<QMdiSubWindow *>();
+    QSignalSpy spy(&mdiArea, SIGNAL(subWindowActivated(QMdiSubWindow*)));
+    QVERIFY(spy.isValid());
+
+    QEvent event(QEvent::StyleChange);
+    QApplication::sendEvent(sub1, &event);
+    QApplication::sendEvent(sub2, &event);
+
+    // subWindowActivated should NOT be activated by a style change,
+    // even if internally QMdiSubWindow un-minimizes subwindows temporarily.
+    QCOMPARE(spy.count(), 0);
+}
+
 QTEST_MAIN(tst_QMdiSubWindow)
 #include "tst_qmdisubwindow.moc"