When reparenting native widget, delayed deletion of Symbian control

until control returns to the event loop.

This is necessary because reparenting can be triggered from the context
of a control's event handler.  If reparenting causes that control to be
deleted, a crash can result.

Task-number: QTBUG-4664
Reviewed-by: axis

5 files changed, 28 insertions, 1 deletions

diff --git a/src/gui/kernel/qapplication_s60.cpp b/src/gui/kernel/qapplication_s60.cpp
index b1706af..1a8aae0 100644
--- a/src/gui/kernel/qapplication_s60.cpp
+++ b/src/gui/kernel/qapplication_s60.cpp
@@ -1122,6 +1122,11 @@ void qt_init(QApplicationPrivate * /* priv */, int)
             ;
     }
 */
+
+    // Register WId with the metatype system.  This is to enable
+    // QWidgetPrivate::create_sys to used delayed slot invokation in order
+    // to destroy WId objects during reparenting.
+    qRegisterMetaType<WId>("WId");
 }
 
 /*****************************************************************************
diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 7c11c00..7c9356e 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -11994,3 +11994,10 @@ void QWidget::clearMask()
     XRender extension is not supported on the X11 display, or if the
     handle could not be created.
 */
+
+#ifdef Q_OS_SYMBIAN
+void QWidgetPrivate::_q_delayedDestroy(WId winId)
+{
+    delete winId;
+}
+#endif
diff --git a/src/gui/kernel/qwidget.h b/src/gui/kernel/qwidget.h
index 76418af..e7daf9f 100644
--- a/src/gui/kernel/qwidget.h
+++ b/src/gui/kernel/qwidget.h
@@ -773,6 +773,9 @@ private:
 private:
     Q_DISABLE_COPY(QWidget)
     Q_PRIVATE_SLOT(d_func(), void _q_showIfNotHidden())
+#ifdef Q_OS_SYMBIAN
+    Q_PRIVATE_SLOT(d_func(), void _q_delayedDestroy(WId winId))
+#endif
 
     QWidgetData *data;
 
diff --git a/src/gui/kernel/qwidget_p.h b/src/gui/kernel/qwidget_p.h
index a4cc0da..c7b8d42 100644
--- a/src/gui/kernel/qwidget_p.h
+++ b/src/gui/kernel/qwidget_p.h
@@ -295,6 +295,7 @@ public:
 #ifdef Q_OS_SYMBIAN
     void setSoftKeys_sys(const QList<QAction*> &softkeys);
     void activateSymbianWindow(WId wid = 0);
+    void _q_delayedDestroy(WId winId);
 #endif
 
     void raise_sys();
diff --git a/src/gui/kernel/qwidget_s60.cpp b/src/gui/kernel/qwidget_s60.cpp
index 5527cc8..c3686b3 100644
--- a/src/gui/kernel/qwidget_s60.cpp
+++ b/src/gui/kernel/qwidget_s60.cpp
@@ -56,6 +56,12 @@
 #include <aknappui.h>
 #endif
 
+// This is necessary in order to be able to perform delayed invokation on slots
+// which take arguments of type WId.  One example is
+// QWidgetPrivate::_q_delayedDestroy, which is used to delay destruction of
+// CCoeControl objects until after the CONE event handler has finished running.
+Q_DECLARE_METATYPE(WId)
+
 QT_BEGIN_NAMESPACE
 
 extern bool qt_nograb();
@@ -438,7 +444,12 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
 
     if (destroyw) {
         destroyw->ControlEnv()->AppUi()->RemoveFromStack(destroyw);
-        CBase::Delete(destroyw);
+
+        // Delay deletion of the control in case this function is called in the
+        // context of a CONE event handler such as
+        // CCoeControl::ProcessPointerEventL
+        QMetaObject::invokeMethod(q, "_q_delayedDestroy",
+            Qt::QueuedConnection, Q_ARG(WId, destroyw));
     }
 
     if (q->testAttribute(Qt::WA_AcceptTouchEvents))