Fix a number of threading data races

Add proper thread termination handler
This partially resolves Bug 1508

20 files changed, 914 insertions, 200 deletions

diff --git a/src/kernel/qapplication.cpp b/src/kernel/qapplication.cpp
index fb531cb..63ddd1e 100644
--- a/src/kernel/qapplication.cpp
+++ b/src/kernel/qapplication.cpp
@@ -377,8 +377,13 @@ int	  QApplication::composedUnicode   = 0;
 
 #ifdef QT_THREAD_SUPPORT
 QMutex *QApplication::qt_mutex		= 0;
-static QMutex *postevent_mutex		= 0;
-static Qt::HANDLE qt_application_thread_id = 0;
+QMutex *qt_sharedStringMutex			= 0;
+Q_EXPORT QMutex * qt_sharedMetaObjectMutex	= 0;
+#ifdef QT_USE_GLIBMAINLOOP
+QMutex *qt_timerListMutex			= 0;
+#endif // QT_USE_GLIBMAINLOOP
+static QMutex *postevent_mutex			= 0;
+static Qt::HANDLE qt_application_thread_id	= 0;
 Q_EXPORT Qt::HANDLE qt_get_application_thread_id()
 {
     return qt_application_thread_id;
@@ -600,6 +605,10 @@ static QPostEventList *globalPostedEvents = 0;	// list of posted events
 
 uint qGlobalPostedEventsCount()
 {
+#ifdef QT_THREAD_SUPPORT
+    QMutexLocker locker( postevent_mutex );
+#endif // QT_THREAD_SUPPORT
+
     if (!globalPostedEvents) {
 	return 0;
     }
@@ -1015,6 +1024,11 @@ void QApplication::initialize( int argc, char **argv )
 {
 #ifdef QT_THREAD_SUPPORT
     qt_mutex = new QMutex( TRUE );
+    qt_sharedStringMutex = new QMutex( TRUE );
+    qt_sharedMetaObjectMutex = new QMutex( TRUE );
+#ifdef QT_USE_GLIBMAINLOOP
+    qt_timerListMutex = new QMutex( TRUE );
+#endif // QT_USE_GLIBMAINLOOP
     postevent_mutex = new QMutex( TRUE );
     qt_application_thread_id = QThread::currentThread();
 #endif // QT_THREAD_SUPPORT
@@ -1184,6 +1198,17 @@ QApplication::~QApplication()
     session_key = 0;
 #endif //QT_NO_SESSIONMANAGER
 
+#ifdef QT_THREAD_SUPPORT
+    delete qt_sharedMetaObjectMutex;
+    qt_sharedMetaObjectMutex = 0;
+    delete qt_sharedStringMutex;
+    qt_sharedStringMutex = 0;
+#ifdef QT_USE_GLIBMAINLOOP
+    delete qt_timerListMutex;
+    qt_timerListMutex = 0;
+#endif // QT_USE_GLIBMAINLOOP
+#endif // QT_THREAD_SUPPORT
+
     qt_explicit_app_style = FALSE;
     qt_app_has_font = FALSE;
     app_tracking = 0;
@@ -2425,35 +2450,40 @@ bool QApplication::notify( QObject *receiver, QEvent *e )
 	return FALSE;
     }
 
-    if ( e->type() == QEvent::ChildRemoved && receiver->postedEvents && globalPostedEvents) {
+    if ( receiver && (e->type() == QEvent::Destroy) ) {
+	return TRUE;
+    }
 
+    if ( e->type() == QEvent::ChildRemoved && receiver->postedEvents) {
 #ifdef QT_THREAD_SUPPORT
 	QMutexLocker locker( postevent_mutex );
 #endif // QT_THREAD_SUPPORT
 
-	// the QObject destructor calls QObject::removeChild, which calls
-	// QApplication::sendEvent() directly.  this can happen while the event
-	// loop is in the middle of posting events, and when we get here, we may
-	// not have any more posted events for this object.
-	if ( receiver->postedEvents ) {
-	    // if this is a child remove event and the child insert
-	    // hasn't been dispatched yet, kill that insert
-	    QPostEventList * l = receiver->postedEvents;
-	    QObject * c = ((QChildEvent*)e)->child();
-	    QPostEvent * pe;
-	    l->first();
-	    while( ( pe = l->current()) != 0 ) {
-		if ( pe->event && pe->receiver == receiver &&
-		     pe->event->type() == QEvent::ChildInserted &&
-		     ((QChildEvent*)pe->event)->child() == c ) {
-		    pe->event->posted = FALSE;
-		    delete pe->event;
-		    pe->event = 0;
-		    l->remove();
-		    continue;
+	if (globalPostedEvents) {
+		// the QObject destructor calls QObject::removeChild, which calls
+		// QApplication::sendEvent() directly.  this can happen while the event
+		// loop is in the middle of posting events, and when we get here, we may
+		// not have any more posted events for this object.
+		if ( receiver->postedEvents ) {
+			// if this is a child remove event and the child insert
+			// hasn't been dispatched yet, kill that insert
+			QPostEventList * l = receiver->postedEvents;
+			QObject * c = ((QChildEvent*)e)->child();
+			QPostEvent * pe;
+			l->first();
+			while( ( pe = l->current()) != 0 ) {
+				if ( pe->event && pe->receiver == receiver &&
+					pe->event->type() == QEvent::ChildInserted &&
+					((QChildEvent*)pe->event)->child() == c ) {
+					pe->event->posted = FALSE;
+					delete pe->event;
+					pe->event = 0;
+					l->remove();
+					continue;
+				}
+				l->next();
+			}
 		}
-		l->next();
-	    }
 	}
     }
 
@@ -3545,8 +3575,9 @@ void QApplication::removePostedEvents( QObject *receiver )
 
 void QApplication::removePostedEvents( QObject *receiver, int event_type )
 {
-    if ( !receiver )
+    if ( !receiver ) {
 	return;
+    }
 
 #ifdef QT_THREAD_SUPPORT
     QMutexLocker locker( postevent_mutex );
@@ -3556,8 +3587,9 @@ void QApplication::removePostedEvents( QObject *receiver, int event_type )
     // happen while the event loop is in the middle of posting events,
     // and when we get here, we may not have any more posted events
     // for this object.
-    if ( !receiver->postedEvents )
+    if ( !receiver->postedEvents ) {
 	return;
+    }
 
     // iterate over the object-specifc list and delete the events.
     // leave the QPostEvent objects; they'll be deleted by
@@ -3596,8 +3628,13 @@ void QApplication::removePostedEvents( QObject *receiver, int event_type )
 
 void QApplication::removePostedEvent( QEvent *  event )
 {
-    if ( !event || !event->posted )
+    if ( !event || !event->posted ) {
 	return;
+    }
+
+#ifdef QT_THREAD_SUPPORT
+    QMutexLocker locker( postevent_mutex );
+#endif // QT_THREAD_SUPPORT
 
     if ( !globalPostedEvents ) {
 #if defined(QT_DEBUG)
@@ -3607,10 +3644,6 @@ void QApplication::removePostedEvent( QEvent *  event )
 #endif
     }
 
-#ifdef QT_THREAD_SUPPORT
-    QMutexLocker locker( postevent_mutex );
-#endif // QT_THREAD_SUPPORT
-
     QPostEventListIt it( *globalPostedEvents );
     QPostEvent * pe;
     while( (pe = it.current()) != 0 ) {
@@ -3696,6 +3729,51 @@ void QApplication::removePostedEvent( QEvent *  event )
     }
 }
 
+void qThreadTerminationHandlerRecursive( QObject* object, QThread* originThread, QThread* destinationThread ) {
+#ifdef QT_THREAD_SUPPORT
+	QThread* objectThread = object->contextThreadObject();
+	if (objectThread != destinationThread) {
+		QThread::CleanupType cleanupType = objectThread->cleanupType();
+		if (cleanupType == QThread::CleanupMergeObjects) {
+			object->moveToThread(destinationThread);
+		}
+		else if (cleanupType == QThread::CleanupNone) {
+			// Do nothing
+#if defined(QT_DEBUG)
+			qDebug( "QApplication::threadTerminationHandler: object %p still owned by thread %p at thread termination!",  object, objectThread);
+#endif // QT_DEBUG
+		}
+		else {
+			// Do nothing
+#if defined(QT_DEBUG)
+			qDebug( "QApplication::threadTerminationHandler: invalid thread termination cleanup type %d specified",  cleanupType);
+#endif // QT_DEBUG
+		}
+	}
+	QObjectList children = object->childrenListObject();
+	QObject *childObject;
+	for ( childObject = children.first(); childObject; childObject = children.next() ) {
+		qThreadTerminationHandlerRecursive(childObject, originThread, destinationThread);
+	}
+#endif // QT_THREAD_SUPPORT
+}
+
+/*!\internal
+
+  Migrates all objects from the specified thread in preparation
+  for thread destruction.
+ */
+void QApplication::threadTerminationHandler( QThread *originThread ) {
+#ifdef QT_THREAD_SUPPORT
+	QMutexLocker locker( qt_mutex );
+	QThread* destinationThread = guiThread();
+	const QObjectList* objects = QObject::objectTrees();
+	for ( QObjectListIt objectit( *objects ) ; *objectit; ++objectit ) {
+		qThreadTerminationHandlerRecursive((*objectit), originThread, destinationThread);
+	}
+#endif // QT_THREAD_SUPPORT
+}
+
 /*!\internal
 
   Sets the active window in reaction to a system event. Call this
diff --git a/src/kernel/qapplication.h b/src/kernel/qapplication.h
index 5611164..f05dbc3 100644
--- a/src/kernel/qapplication.h
+++ b/src/kernel/qapplication.h
@@ -352,11 +352,12 @@ private slots:
     void postIMEvent( QObject *receiver, QIMEvent *event );
 #endif
 
-private:
+public:
 #ifdef QT_THREAD_SUPPORT
     static QMutex   *qt_mutex;
 #endif // QT_THREAD_SUPPORT
 
+private:
     int		     app_argc;
     char	   **app_argv;
     bool	     quit_now;
@@ -434,6 +435,7 @@ private:
     friend class QDialog;
     friend class QAccelManager;
     friend class QEvent;
+    friend class QThread;
     friend class QTranslator;
     friend class QEventLoop;
     friend Q_EXPORT void qt_ucm_initialize( QApplication * );
@@ -457,6 +459,7 @@ public:
     static QThread* guiThread();
 #endif
     static bool isGuiThread();
+    static void threadTerminationHandler( QThread * );
 };
 
 inline int QApplication::argc() const
diff --git a/src/kernel/qeventloop_unix_glib.cpp b/src/kernel/qeventloop_unix_glib.cpp
index 1c491cf..6924fcd 100644
--- a/src/kernel/qeventloop_unix_glib.cpp
+++ b/src/kernel/qeventloop_unix_glib.cpp
@@ -55,6 +55,12 @@
 
 #include <glib.h>
 
+#ifdef QT_THREAD_SUPPORT
+#ifdef QT_USE_GLIBMAINLOOP
+extern QMutex *qt_timerListMutex;
+#endif // QT_USE_GLIBMAINLOOP
+#endif // QT_THREAD_SUPPORT
+
 /*****************************************************************************
   Timer handling; UNIX has no application timer support so we'll have to
   make our own from scratch.
@@ -102,9 +108,6 @@ typedef QPtrList<TimerInfo> TimerList;		// list of TimerInfo structs
 
 static QBitArray *timerBitVec;			// timer bit vector
 static TimerList  *timerList = 0;		// timer list
-#if defined(QT_THREAD_SUPPORT)
-static QMutex    *timerListMutex = 0;		// timer list mutex
-#endif
 
 static void initTimers();
 void cleanupTimers();
@@ -184,7 +187,7 @@ static int allocTimerId()			// find avail timer identifier
 static void insertTimer( const TimerInfo *ti )				// insert timer info into list
 {
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->lock();
+	qt_timerListMutex->lock();
 #endif
 	TimerInfo *t = timerList->first();
 	int index = 0;
@@ -207,7 +210,7 @@ static void insertTimer( const TimerInfo *ti )				// insert timer info into list
 	}
 #endif
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->unlock();
+	qt_timerListMutex->unlock();
 #endif
 }
 
@@ -233,7 +236,7 @@ static inline void getTime( timeval &t )				// get time of day
 static void repairTimer( const timeval &time )				// repair broken timer
 {
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->lock();
+	qt_timerListMutex->lock();
 #endif
 	timeval diff = watchtime - time;
 	register TimerInfo *t = timerList->first();
@@ -242,7 +245,7 @@ static void repairTimer( const timeval &time )				// repair broken timer
 		t = timerList->next();
 	}
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->unlock();
+	qt_timerListMutex->unlock();
 #endif
 }
 
@@ -260,7 +263,7 @@ static void repairTimer( const timeval &time )				// repair broken timer
 timeval *qt_wait_timer()
 {
 #if defined(QT_THREAD_SUPPORT)
-	if (timerListMutex) timerListMutex->lock();
+	qt_timerListMutex->lock();
 #endif
 	static timeval tm;
 	bool first = TRUE;
@@ -286,19 +289,19 @@ timeval *qt_wait_timer()
 			tm = *qt_wait_timer_max;
 		}
 #if defined(QT_THREAD_SUPPORT)
-		if (timerListMutex) timerListMutex->unlock();
+		qt_timerListMutex->unlock();
 #endif
 		return &tm;
 	}
 	if ( qt_wait_timer_max ) {
 		tm = *qt_wait_timer_max;
 #if defined(QT_THREAD_SUPPORT)
-		if (timerListMutex) timerListMutex->unlock();
+		qt_timerListMutex->unlock();
 #endif
 		return &tm;
 	}
 #if defined(QT_THREAD_SUPPORT)
-	if (timerListMutex) timerListMutex->unlock();
+	qt_timerListMutex->unlock();
 #endif
 	return 0;							// no timers
 }
@@ -314,7 +317,7 @@ static void initTimers()						// initialize timers
 	}
 	timerList = new TimerList;
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex = new QMutex(true);
+	qt_timerListMutex = new QMutex(true);
 #endif
 	Q_CHECK_PTR( timerList );
 	timerList->setAutoDelete( TRUE );
@@ -328,20 +331,25 @@ void cleanupTimers()
 	timerList = 0;
 	delete timerBitVec;
 	timerBitVec = 0;
-#if defined(QT_THREAD_SUPPORT)
-	delete timerListMutex;
-	timerListMutex = 0;
-#endif
 }
 
 // Main timer functions for starting and killing timers
 int qStartTimer( int interval, QObject *obj )
 {
+#if defined(QT_THREAD_SUPPORT)
+	if (qt_timerListMutex) qt_timerListMutex->lock();
+#endif
 	if ( !timerList ) {						// initialize timer data
 		initTimers();
+#if defined(QT_THREAD_SUPPORT)
+		if (qt_timerListMutex) qt_timerListMutex->lock();
+#endif
 	}
 	int id = allocTimerId();					// get free timer id
 	if ( (id <= 0) || (id > (int)timerBitVec->size()) || (!obj) ) {	// cannot create timer
+#if defined(QT_THREAD_SUPPORT)
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
+#endif
 		return 0;
 	}
 	timerBitVec->setBit( id-1 );					// set timer active
@@ -355,18 +363,24 @@ int qStartTimer( int interval, QObject *obj )
 	t->timeout = currentTime + t->interval;
 	t->obj = obj;
 	insertTimer( t );						// put timer in list
+#if defined(QT_THREAD_SUPPORT)
+	if (qt_timerListMutex) qt_timerListMutex->unlock();
+#endif
 	return id;
 }
 
 bool qKillTimer( int id )
 {
+#if defined(QT_THREAD_SUPPORT)
+	if (qt_timerListMutex) qt_timerListMutex->lock();
+#endif
 	register TimerInfo *t;
 	if ( (!timerList) || (id <= 0) || (id > (int)timerBitVec->size()) || (!timerBitVec->testBit( id-1 )) ) {
-		return FALSE;						// not init'd or invalid timer
-	}
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->lock();
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
+		return FALSE;						// not init'd or invalid timer
+	}
 	t = timerList->first();
 	while ( t && t->id != id ) {					// find timer info in list
 		t = timerList->next();
@@ -376,13 +390,13 @@ bool qKillTimer( int id )
 		timerBitVec->clearBit( id-1 );				// set timer inactive
 		ret = timerList->remove();
 #if defined(QT_THREAD_SUPPORT)
-		timerListMutex->unlock();
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
 		return ret;
 	}
 	else {								// id not found
 #if defined(QT_THREAD_SUPPORT)
-		timerListMutex->unlock();
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
 		return FALSE;
 	}
@@ -390,13 +404,16 @@ bool qKillTimer( int id )
 
 bool qKillTimer( QObject *obj )
 {
+#if defined(QT_THREAD_SUPPORT)
+	if (qt_timerListMutex) qt_timerListMutex->lock();
+#endif
 	register TimerInfo *t;
 	if ( !timerList ) {						// not initialized
-		return FALSE;
-	}
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->lock();
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
+		return FALSE;
+	}
 	t = timerList->first();
 	while ( t ) {							// check all timers
 		if ( t->obj == obj ) {					// object found
@@ -409,7 +426,7 @@ bool qKillTimer( QObject *obj )
 		}
 	}
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->unlock();
+	if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
 	return TRUE;
 }
@@ -615,12 +632,15 @@ int QEventLoop::timeToWait() const
 
 int QEventLoop::activateTimers()
 {
+#if defined(QT_THREAD_SUPPORT)
+	if (qt_timerListMutex) qt_timerListMutex->lock();
+#endif
 	if ( !timerList || !timerList->count() ) {		// no timers
-		return 0;
-	}
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->lock();
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
+		return 0;
+	}
 	bool first = TRUE;
 	timeval currentTime;
 	int n_act = 0, maxCount = timerList->count();
@@ -663,7 +683,7 @@ int QEventLoop::activateTimers()
 			n_act++;
 		}
 #if defined(QT_THREAD_SUPPORT)
-		timerListMutex->unlock();
+		if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
 		QTimerEvent e( t->id );
 #if defined(QT_THREAD_SUPPORT)
@@ -678,14 +698,14 @@ int QEventLoop::activateTimers()
 		QApplication::sendEvent( t->obj, &e );					// send event
 #endif // defined(QT_THREAD_SUPPORT)
 #if defined(QT_THREAD_SUPPORT)
-		timerListMutex->lock();
+		if (qt_timerListMutex) qt_timerListMutex->lock();
 #endif
 		if ( timerList->findRef( begin ) == -1 ) {
 			begin = 0;
 		}
 	}
 #if defined(QT_THREAD_SUPPORT)
-	timerListMutex->unlock();
+	if (qt_timerListMutex) qt_timerListMutex->unlock();
 #endif
 	return n_act;
 }
diff --git a/src/kernel/qeventloop_x11_glib.cpp b/src/kernel/qeventloop_x11_glib.cpp
index 23162c7..2bf1f63 100644
--- a/src/kernel/qeventloop_x11_glib.cpp
+++ b/src/kernel/qeventloop_x11_glib.cpp
@@ -629,6 +629,10 @@ bool QEventLoop::gsourceDispatch(GSource *gs) {
 
 bool QEventLoop::hasPendingEvents() const
 {
+#ifdef QT_THREAD_SUPPORT
+	QMutexLocker locker( QApplication::qt_mutex );
+#endif // QT_THREAD_SUPPORT
+
 	extern uint qGlobalPostedEventsCount(); // from qapplication.cpp
 	return ( qGlobalPostedEventsCount() || ( (qt_is_gui_used && QApplication::isGuiThread())  ? XPending( QPaintDevice::x11AppDisplay() ) : 0));
 }
diff --git a/src/kernel/qobject.cpp b/src/kernel/qobject.cpp
index a3f4f18..9e5ac8e 100644
--- a/src/kernel/qobject.cpp
+++ b/src/kernel/qobject.cpp
@@ -73,6 +73,8 @@ public:
     }
 #endif
     QThread* ownThread;
+    QMutex* senderObjectListMutex;
+    QMutex* childObjectListMutex;
     bool disableThreadPostedEvents;
 };
 
@@ -83,6 +85,10 @@ void QObject::moveToThread_helper(QThread *targetThread)
     QEvent e(QEvent::ThreadChange);
     QApplication::sendEvent(this, &e);
 
+#ifdef QT_THREAD_SUPPORT
+    QMutexLocker locker( d->childObjectListMutex );
+#endif // QT_THREAD_SUPPORT
+
     if (childObjects) {
         QObject *child;
         QObjectListIt it(*childObjects);
@@ -97,12 +103,16 @@ void QObject::setThreadObject_helper(QThread *targetThread)
 {
     d->ownThread = targetThread;
 
+#ifdef QT_THREAD_SUPPORT
+    QMutexLocker locker( d->childObjectListMutex );
+#endif // QT_THREAD_SUPPORT
+
     if (childObjects) {
         QObject *child;
         QObjectListIt it(*childObjects);
         while ( (child=it.current()) ) {
             ++it;
-            child->moveToThread_helper(targetThread);
+            child->setThreadObject_helper(targetThread);
         }
     }
 }
@@ -123,7 +133,9 @@ void QObject::setThreadObject_helper(QThread *targetThread)
  */
 void QObject::moveToThread(QThread *targetThread)
 {
+#ifdef QT_THREAD_SUPPORT
     QMutexLocker locker( QApplication::qt_mutex );
+#endif // QT_THREAD_SUPPORT
 
     if (parentObj) {
 #if defined(QT_DEBUG)
@@ -179,11 +191,23 @@ void QObject::disableThreadPostedEvents(bool disable) {
 
 class QSenderObjectList : public QObjectList, public QShared
 {
-public:
-    QSenderObjectList() : currentSender( 0 ) { }
-    QObject *currentSender;
+	public:
+		QSenderObjectList();
+		~QSenderObjectList();
+	
+	public:
+		QObject *currentSender;
+		QMutex *listMutex;
 };
 
+QSenderObjectList::QSenderObjectList() : currentSender( 0 ) {
+	listMutex = new QMutex( TRUE );
+}
+
+QSenderObjectList::~QSenderObjectList() {
+	delete listMutex;
+}
+
 class Q_EXPORT QMetaCallEvent : public QEvent
 {
 public:
@@ -369,8 +393,9 @@ bool  qKillTimer( QObject *obj );
 static void removeObjFromList( QObjectList *objList, const QObject *obj,
 			       bool single=FALSE )
 {
-    if ( !objList )
+    if ( !objList ) {
 	return;
+    }
     int index = objList->findRef( obj );
     while ( index >= 0 ) {
 	objList->remove();
@@ -585,20 +610,25 @@ QObject::QObject( QObject *parent, const char *name )
     postedEvents( 0 ), 				// no events posted
     d( 0 )
 {
-    if ( !metaObj )				// will create object dict
+    if ( !d ) {
+	d = new QObjectPrivate(0);
+    }
+
+    d->ownThread = QThread::currentThreadObject();
+    d->senderObjectListMutex = new QMutex( TRUE );
+    d->childObjectListMutex = new QMutex( TRUE );
+
+    if ( !metaObj ) {				// will create object dict
 	(void) staticMetaObject();
+    }
 
     if ( parent ) {				// add object to parent
 	parent->insertChild( this );
-    } else {
+    }
+    else {
 	insert_tree( this );
 	isTree = TRUE;
     }
-
-    if ( !d )
-	d = new QObjectPrivate(0);
-
-    d->ownThread = QThread::currentThreadObject();
 }
 
 
@@ -630,10 +660,15 @@ QObject::~QObject()
 #endif
 	return;
     }
+    if (qApp) {
+	QEvent destroyEvent(QEvent::Destroy);
+	qApp->notify(this, &destroyEvent);
+    }
     wasDeleted = 1;
     blockSig = 0; // unblock signals to keep QGuardedPtr happy
     emit destroyed( this );
     emit destroyed();
+
     if ( objname ) {
 	delete [] (char*)objname;
     }
@@ -669,8 +704,9 @@ QObject::~QObject()
 	    QConnectionListIt cit(*clist);
 	    while( (c=cit.current()) ) {	// for each connected slot...
 		++cit;
-		if ( (obj=c->object()) )
+		if ( (obj=c->object()) ) {
 		    removeObjFromList( obj->senderObjects, this );
+		}
 	    }
 	}
 	delete connections;
@@ -691,6 +727,11 @@ QObject::~QObject()
 	delete childObjects;
     }
 
+#ifdef QT_THREAD_SUPPORT
+    delete d->childObjectListMutex;
+    delete d->senderObjectListMutex;
+#endif // QT_THREAD_SUPPORT
+
     delete d;
 }
 
@@ -985,11 +1026,17 @@ bool QObject::event( QEvent *e )
 		    QSenderObjectList* sol;
 		    QObject* oldSender = 0;
 		    sol = senderObjects;
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		    if ( sol ) {
 			oldSender = sol->currentSender;
 			sol->ref();
 			sol->currentSender = metaEvent->sender();
 		    }
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		    QUObject *o = metaEvent->data();
 		    if (metaEvent->type() == QMetaCallEvent::MetaCallEmit) {
 			qt_emit( metaEvent->id(), o );
@@ -997,12 +1044,20 @@ bool QObject::event( QEvent *e )
 		    if (metaEvent->type() == QMetaCallEvent::MetaCallInvoke) {
 			qt_invoke( metaEvent->id(), o );
 		    }
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		    if (sol ) {
 			sol->currentSender = oldSender;
 			if ( sol->deref() ) {
+			    sol->listMutex->unlock();
 			    delete sol;
+			    sol = NULL;
 			}
 		    }
+#ifdef QT_THREAD_SUPPORT
+		    if (sol) sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		}
 		else {
 		    qWarning("QObject: Ignoring metacall event from non-owning thread");
@@ -1509,6 +1564,10 @@ QConnectionList *QObject::receivers( int signal ) const
 
 void QObject::insertChild( QObject *obj )
 {
+#ifdef QT_THREAD_SUPPORT
+	QMutexLocker locker( d->childObjectListMutex );
+#endif // QT_THREAD_SUPPORT
+
     if ( obj->isTree ) {
 	remove_tree( obj );
 	obj->isTree = FALSE;
@@ -1551,6 +1610,10 @@ void QObject::insertChild( QObject *obj )
 
 void QObject::removeChild( QObject *obj )
 {
+#ifdef QT_THREAD_SUPPORT
+	QMutexLocker locker( d->childObjectListMutex );
+#endif // QT_THREAD_SUPPORT
+
     if ( childObjects && childObjects->removeRef(obj) ) {
 	obj->parentObj = 0;
 	if ( !obj->wasDeleted ) {
@@ -2135,9 +2198,25 @@ void QObject::connectInternal( const QObject *sender, int signal_index, const QO
     QConnection *c = new QConnection( r, member_index, rm ? rm->name : "qt_invoke", membcode );
     Q_CHECK_PTR( c );
     clist->append( c );
-    if ( !r->senderObjects )			// create list of senders
+    if ( !r->senderObjects ) {			// create list of senders
+#ifdef QT_THREAD_SUPPORT
+	r->d->senderObjectListMutex->lock();
+#endif // QT_THREAD_SUPPORT
 	r->senderObjects = new QSenderObjectList;
+#ifdef QT_THREAD_SUPPORT
+	r->senderObjects->listMutex->lock();
+	r->d->senderObjectListMutex->unlock();
+#endif // QT_THREAD_SUPPORT
+    }
+    else {
+#ifdef QT_THREAD_SUPPORT
+	r->senderObjects->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
+    }
     r->senderObjects->append( s );		// add sender to list
+#ifdef QT_THREAD_SUPPORT
+    r->senderObjects->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 }
 
 
@@ -2343,13 +2422,25 @@ bool QObject::disconnectInternal( const QObject *sender, int signal_index,
 	    c = clist->first();
 	    while ( c ) {			// for all receivers...
 		if ( r == 0 ) {			// remove all receivers
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		    removeObjFromList( c->object()->senderObjects, s );
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		    success = TRUE;
 		    c = clist->next();
 		} else if ( r == c->object() &&
 			    ( (member_index == -1) ||
 			      ((member_index == c->member()) && (c->memberType() == membcode)) ) ) {
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		    removeObjFromList( c->object()->senderObjects, s, TRUE );
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		    success = TRUE;
 		    clist->remove();
 		    c = clist->current();
@@ -2368,13 +2459,25 @@ bool QObject::disconnectInternal( const QObject *sender, int signal_index,
 	c = clist->first();
 	while ( c ) {				// for all receivers...
 	    if ( r == 0 ) {			// remove all receivers
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		removeObjFromList( c->object()->senderObjects, s, TRUE );
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		success = TRUE;
 		c = clist->next();
 	    } else if ( r == c->object() &&
 			( (member_index == -1) ||
 			  ((member_index == c->member()) && (c->memberType() == membcode)) ) ) {
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		removeObjFromList( c->object()->senderObjects, s, TRUE );
+#ifdef QT_THREAD_SUPPORT
+		    if (c->object()->senderObjects) c->object()->senderObjects->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		success = TRUE;
 		clist->remove();
 		c = clist->current();
@@ -2382,8 +2485,9 @@ bool QObject::disconnectInternal( const QObject *sender, int signal_index,
 		c = clist->next();
 	    }
 	}
-	if ( r == 0 )				// disconnect all receivers
+	if ( r == 0 ) {				// disconnect all receivers
 	    s->connections->insert( signal_index, 0 );
+	}
     }
     return success;
 }
@@ -2578,11 +2682,13 @@ void QObject::activate_signal( int signal )
     }
 #endif
 
-    if ( !connections || signalsBlocked() || signal < 0 )
+    if ( !connections || signalsBlocked() || signal < 0 ) {
 	return;
+    }
     QConnectionList *clist = connections->at( signal );
-    if ( !clist )
+    if ( !clist ) {
 	return;
+    }
     QUObject o[1];
     o[0].isLastObject = true;
     activate_signal( clist, o );
@@ -2592,12 +2698,14 @@ void QObject::activate_signal( int signal )
 
 void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 {
-    if ( !clist )
+    if ( !clist ) {
 	return;
+    }
 
 #ifndef QT_NO_PRELIMINARY_SIGNAL_SPY
-    if ( qt_preliminary_signal_spy )
+    if ( qt_preliminary_signal_spy ) {
 	qt_spy_signal( this, connections->findRef( clist), o );
+    }
 #endif
 
     const QThread *currentThread = QThread::currentThreadObject();
@@ -2610,6 +2718,9 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	c = clist->first();
 	object = c->object();
 	sol = object->senderObjects;
+#ifdef QT_THREAD_SUPPORT
+	sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 	if ( sol ) {
 	    oldSender = sol->currentSender;
 	    sol->ref();
@@ -2617,7 +2728,13 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	}
 	if ( c->memberType() == QSIGNAL_CODE ) {
 	    if ((d->disableThreadPostedEvents) || (object->d->ownThread == currentThread)) {
+#ifdef QT_THREAD_SUPPORT
+		sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		object->qt_emit( c->member(), o );
+#ifdef QT_THREAD_SUPPORT
+		sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 	    }
 	    else {
 		if (object->d->ownThread && !object->d->ownThread->finished()) {
@@ -2627,7 +2744,13 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	}
 	else {
 	    if ((d->disableThreadPostedEvents) || (object->d->ownThread == currentThread)) {
+#ifdef QT_THREAD_SUPPORT
+		sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		object->qt_invoke( c->member(), o );
+#ifdef QT_THREAD_SUPPORT
+		sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 	    }
 	    else {
 		if (object->d->ownThread && !object->d->ownThread->finished()) {
@@ -2637,9 +2760,15 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	}
 	if ( sol ) {
 	    sol->currentSender = oldSender;
-	    if ( sol->deref() )
+	    if ( sol->deref() ) {
+	        sol->listMutex->unlock();
 		delete sol;
+		sol = NULL;
+	    }
 	}
+#ifdef QT_THREAD_SUPPORT
+	if (sol) sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
     } else {
 	QConnection *cd = 0;
 	QConnectionListIt it(*clist);
@@ -2650,6 +2779,9 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	    cd = c;
 	    object = c->object();
 	    sol = object->senderObjects;
+#ifdef QT_THREAD_SUPPORT
+	sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 	    if ( sol ) {
 		oldSender = sol->currentSender;
 		sol->ref();
@@ -2657,7 +2789,13 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	    }
 	    if ( c->memberType() == QSIGNAL_CODE ) {
 		if ((d->disableThreadPostedEvents) || (object->d->ownThread == currentThread)) {
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		    object->qt_emit( c->member(), o );
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		}
 		else {
 		    if (object->d->ownThread && !object->d->ownThread->finished()) {
@@ -2667,7 +2805,13 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	    }
 	    else {
 		if ((d->disableThreadPostedEvents) || (object->d->ownThread == currentThread)) {
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 		    object->qt_invoke( c->member(), o );
+#ifdef QT_THREAD_SUPPORT
+		    sol->listMutex->lock();
+#endif // QT_THREAD_SUPPORT
 		}
 		else {
 		    if (object->d->ownThread && !object->d->ownThread->finished()) {
@@ -2677,9 +2821,15 @@ void QObject::activate_signal( QConnectionList *clist, QUObject *o )
 	    }
 	    if (sol ) {
 		sol->currentSender = oldSender;
-		if ( sol->deref() )
+		if ( sol->deref() ) {
+		    sol->listMutex->unlock();
 		    delete sol;
+		    sol = NULL;
+		}
 	    }
+#ifdef QT_THREAD_SUPPORT
+	    if (sol) sol->listMutex->unlock();
+#endif // QT_THREAD_SUPPORT
 	}
     }
 }
@@ -2818,6 +2968,10 @@ void QObject::dumpObjectTree()
 
 void QObject::dumpObjectInfo()
 {
+#ifdef QT_THREAD_SUPPORT
+    QMutexLocker locker( d->senderObjectListMutex );
+#endif // QT_THREAD_SUPPORT
+
 #if defined(QT_DEBUG)
     qDebug( "OBJECT %s::%s", className(), name( "unnamed" ) );
     int n = 0;
@@ -2852,8 +3006,9 @@ void QObject::dumpObjectInfo()
 	    sender = senderObjects->next();
 	}
     }
-    if ( n == 0 )
+    if ( n == 0 ) {
 	qDebug( "\t<None>" );
+    }
 #endif
 }
 
diff --git a/src/kernel/qobject.h b/src/kernel/qobject.h
index 89cbfe2..a63fc4d 100644
--- a/src/kernel/qobject.h
+++ b/src/kernel/qobject.h
@@ -46,6 +46,7 @@
 #include "qwindowdefs.h"
 #include "qstring.h"
 #include "qevent.h"
+#include "qmutex.h"
 #include "qnamespace.h"
 #endif // QT_H
 
diff --git a/src/kernel/qobjectdefs.h b/src/kernel/qobjectdefs.h
index 37605bd..cab0ec0 100644
--- a/src/kernel/qobjectdefs.h
+++ b/src/kernel/qobjectdefs.h
@@ -157,6 +157,7 @@ class QMetaObject;
 class QSignal;
 class QConnection;
 class QEvent;
+class QMutex;
 struct QMetaData;
 class QConnectionList;
 class QConnectionListIt;
@@ -165,6 +166,8 @@ class QObjectList;
 class QObjectListIt;
 class QMemberDict;
 
+extern QMutex *qt_sharedMetaObjectMutex;
+
 Q_EXPORT void *qt_find_obj_child( QObject *, const char *, const char * );
 #define Q_CHILD(parent,type,name) \
 	((type*)qt_find_obj_child(parent,#type,name))
diff --git a/src/kernel/qstyle.cpp b/src/kernel/qstyle.cpp
index c7f4ef4..ebc7e5b 100644
--- a/src/kernel/qstyle.cpp
+++ b/src/kernel/qstyle.cpp
@@ -62,6 +62,194 @@ public:
     }
 };
 
+QStyleOption::QStyleOption(StyleOptionDefault) :
+	def(TRUE),
+	tb(NULL),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(int in1) :
+	def(FALSE),
+	tb(NULL),
+	i1(in1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(int in1, int in2) :
+	def(FALSE),
+	tb(NULL),
+	i1(in1),
+	i2(in2),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(int in1, int in2, int in3, int in4) :
+	def(FALSE),
+	tb(NULL),
+	i1(in1),
+	i2(in2),
+	i3(in3),
+	i4(in4),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QMenuItem* m) :
+	def(FALSE),
+	mi(m),
+	tb(NULL),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QMenuItem* m, int in1) :
+	def(FALSE),
+	mi(m),
+	tb(NULL),
+	i1(in1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QMenuItem* m, int in1, int in2) :
+	def(FALSE),
+	mi(m),
+	tb(NULL),
+	i1(in1),
+	i2(in2),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(const QColor& c) :
+	def(FALSE),
+	tb(NULL),
+	cl(&c),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QTab* t) :
+	def(FALSE),
+	tb(t),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QListViewItem* i) :
+	def(FALSE),
+	tb(NULL),
+	li(i),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QCheckListItem* i) :
+	def(FALSE),
+	tb(NULL),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(i),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(Qt::ArrowType a) :
+	def(FALSE),
+	tb(NULL),
+	i1((int)a),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(const QRect& r) :
+	def(FALSE),
+	tb(NULL),
+	i1(r.x()),
+	i2(r.y()),
+	i3(r.width()),
+	i4(r.height()),
+	i5(-1),
+	cli(NULL),
+	tbh(NULL) {
+	//
+}
+
+QStyleOption::QStyleOption(QWidget *w) :
+	def(FALSE),
+	tb(NULL),
+	i1(-1),
+	i2(-1),
+	i3(-1),
+	i4(-1),
+	i5(-1),
+	cli(NULL),
+	p1((void*)w),
+	tbh(NULL) {
+	//
+}
+
 /*!
     \class QStyleOption qstyle.h
     \brief The QStyleOption class specifies optional parameters for QStyle functions.
diff --git a/src/kernel/qstyle.h b/src/kernel/qstyle.h
index 0efc386..c38f403 100644
--- a/src/kernel/qstyle.h
+++ b/src/kernel/qstyle.h
@@ -59,30 +59,24 @@ class QTab;
 class QListViewItem;
 class QCheckListItem;
 
-class QStyleOption {
+class Q_EXPORT QStyleOption {
 public:
     enum StyleOptionDefault { Default };
 
-    QStyleOption(StyleOptionDefault=Default) : def(TRUE), tb(NULL), cli(NULL), tbh(NULL) {}
-
-    // Note: we don't use default arguments since that is unnecessary
-    // initialization.
-    QStyleOption(int in1) :
-	def(FALSE), tb(NULL), i1(in1), cli(NULL), tbh(NULL) {}
-    QStyleOption(int in1, int in2) :
-	def(FALSE), tb(NULL), i1(in1), i2(in2), cli(NULL), tbh(NULL) {}
-    QStyleOption(int in1, int in2, int in3, int in4) :
-	def(FALSE), tb(NULL), i1(in1), i2(in2), i3(in3), i4(in4), cli(NULL), tbh(NULL) {}
-    QStyleOption(QMenuItem* m) : def(FALSE), mi(m), tb(NULL), cli(NULL), tbh(NULL) {}
-    QStyleOption(QMenuItem* m, int in1) : def(FALSE), mi(m), tb(NULL), i1(in1), cli(NULL), tbh(NULL) {}
-    QStyleOption(QMenuItem* m, int in1, int in2) : def(FALSE), mi(m), tb(NULL), i1(in1), i2(in2), cli(NULL), tbh(NULL) {}
-    QStyleOption(const QColor& c) : def(FALSE), tb(NULL), cl(&c), cli(NULL), tbh(NULL) {}
-    QStyleOption(QTab* t) : def(FALSE), tb(t), cli(NULL), tbh(NULL) {}
-    QStyleOption(QListViewItem* i) : def(FALSE), tb(NULL), li(i), cli(NULL), tbh(NULL) {}
-    QStyleOption(QCheckListItem* i) : def(FALSE), tb(NULL), cli(i), tbh(NULL) {}
-    QStyleOption(Qt::ArrowType a) : def(FALSE), tb(NULL), i1((int)a), cli(NULL), tbh(NULL) {}
-    QStyleOption(const QRect& r) : def(FALSE), tb(NULL), i1(r.x()), i2(r.y()), i3(r.width()), i4(r.height()), cli(NULL), tbh(NULL) {}
-    QStyleOption(QWidget *w) : def(FALSE), tb(NULL), cli(NULL), p1((void*)w), tbh(NULL) {}
+    QStyleOption(StyleOptionDefault=Default);
+    QStyleOption(int in1);
+    QStyleOption(int in1, int in2);
+    QStyleOption(int in1, int in2, int in3, int in4);
+    QStyleOption(QMenuItem* m);
+    QStyleOption(QMenuItem* m, int in1);
+    QStyleOption(QMenuItem* m, int in1, int in2);
+    QStyleOption(const QColor& c);
+    QStyleOption(QTab* t);
+    QStyleOption(QListViewItem* i);
+    QStyleOption(QCheckListItem* i);
+    QStyleOption(Qt::ArrowType a);
+    QStyleOption(const QRect& r);
+    QStyleOption(QWidget *w);
 
     bool isDefault() const { return def; }
 
diff --git a/src/kernel/qthread.cpp b/src/kernel/qthread.cpp
index cfe8c56..93fc3f2 100644
--- a/src/kernel/qthread.cpp
+++ b/src/kernel/qthread.cpp
@@ -132,6 +132,10 @@
 
 QThread::QThread()
 {
+#ifdef QT_THREAD_SUPPORT
+    QMutexLocker locker( QApplication::qt_mutex );
+#endif // QT_THREAD_SUPPORT
+
     d = new QThreadInstance;
     d->init(0);
 }
diff --git a/src/kernel/qthread.h b/src/kernel/qthread.h
index 0188ea6..80448a0 100644
--- a/src/kernel/qthread.h
+++ b/src/kernel/qthread.h
@@ -108,6 +108,14 @@ public:
     bool finished() const;
     bool running() const;
 
+    enum CleanupType {
+	CleanupNone,
+	CleanupMergeObjects
+    };
+
+    CleanupType cleanupType();
+    void setCleanupType(CleanupType);
+
 protected:
     virtual void run() = 0;
 
diff --git a/src/kernel/qthread_unix.cpp b/src/kernel/qthread_unix.cpp
index 6005c42..59c51f4 100644
--- a/src/kernel/qthread_unix.cpp
+++ b/src/kernel/qthread_unix.cpp
@@ -47,6 +47,7 @@ typedef pthread_mutex_t Q_MUTEX_T;
 #include <private/qmutex_p.h>
 #include <private/qmutexpool_p.h>
 #include <qthreadstorage.h>
+#include <qapplication.h>
 
 #include <errno.h>
 #include <sched.h>
@@ -109,6 +110,7 @@ void QThreadInstance::init(unsigned int stackSize)
     thread_id = 0;
 
     eventLoop = 0;
+    cleanupType = QThread::CleanupMergeObjects;
 
     // threads have not been initialized yet, do it now
     if (! qt_thread_mutexpool) QThread::initialize();
@@ -150,6 +152,8 @@ void QThreadInstance::finish( void * )
 	return;
     }
 
+    QApplication::threadTerminationHandler((QThread*)d->args[0]);
+
     QMutexLocker locker( d->mutex() );
     d->running = FALSE;
     d->finished = TRUE;
@@ -179,7 +183,6 @@ void QThreadInstance::terminate()
     pthread_cancel( thread_id );
 }
 
-
 /**************************************************************************
  ** QThread
  *************************************************************************/
@@ -398,6 +401,9 @@ void QThread::start(Priority priority)
     d->args[0] = this;
     d->args[1] = d;
 #if defined(QT_USE_GLIBMAINLOOP)
+    // The correct thread_id is set in QThreadInstance::start using the value of d->args[1]
+    d->thread_id = NULL;
+
     // Legacy glib versions require this threading system initialization call
     g_thread_init(NULL);
 
@@ -408,8 +414,6 @@ void QThread::start(Priority priority)
     else {
 	ret = -1;
     }
-    // The correct thread_id is set in QThreadInstance::start using the value of d->args[1]
-    d->thread_id = NULL;
 #else // QT_USE_GLIBMAINLOOP
     ret = pthread_create( &d->thread_id, &attr, (QtThreadCallback)QThreadInstance::start, d->args );
 #if defined (Q_OS_HPUX)
@@ -496,6 +500,36 @@ bool QThread::wait( unsigned long time )
 }
 
 /*!
+    Returns the current cleanup behaviour of the thread.
+
+    \sa setCleanupType
+    \sa CleanupType
+*/
+
+QThread::CleanupType QThread::cleanupType() {
+    return (QThread::CleanupType)d->cleanupType;
+}
+
+/*!
+    Sets the current cleanup behaviour of the thread.  The default,
+    QThread::CleanupMergeObjects, will merge any objects owned by this thread
+    with the main GUI thread when this thread is terminated.
+
+    If faster thread termination performance is desired, QThread::CleanupNone
+    may be specified instead.  However, this is not recommended as any objects
+    owned by this thread on termination can then cause events to become "stuck"
+    in the global event queue, leading to high CPU usage and other undesirable
+    behavior.  You have been warned!
+
+    \sa cleanupType
+    \sa CleanupType
+*/
+
+void QThread::setCleanupType(CleanupType type) {
+    d->cleanupType = type;
+}
+
+/*!
     Returns a pointer to the currently executing QThread.  If the
     current thread was not started using the QThread API, this
     function returns zero.
diff --git a/src/moc/moc.y b/src/moc/moc.y
index 316efba..a507126 100644
--- a/src/moc/moc.y
+++ b/src/moc/moc.y
@@ -2986,7 +2986,9 @@ void generateClass()		      // generate C++ source code for a class
 // Generate staticMetaObject member function
 //
     fprintf( out, "QMetaObject* %s::staticMetaObject()\n{\n", (const char*)qualifiedClassName() );
-    fprintf( out, "    if ( metaObj )\n\treturn metaObj;\n" );
+    fprintf( out, "    if ( metaObj ) {\n\treturn metaObj;\n}\n" );
+    fprintf( out, "#ifdef QT_THREAD_SUPPORT\n    if (qt_sharedMetaObjectMutex) qt_sharedMetaObjectMutex->lock();\n" );
+    fprintf( out, "    if ( metaObj ) {\n\tif (qt_sharedMetaObjectMutex) qt_sharedMetaObjectMutex->unlock();\n\treturn metaObj;\n    }\n#endif // QT_THREAD_SUPPORT\n" );
     if ( isQObject )
 	fprintf( out, "    QMetaObject* parentObject = staticQtMetaObject();\n" );
     else if ( !g->superClassName.isEmpty() )
@@ -3056,6 +3058,7 @@ void generateClass()		      // generate C++ source code for a class
 // Setup cleanup handler and return meta object
 //
     fprintf( out, "    cleanUp_%s.setMetaObject( metaObj );\n", cleanup.data() );
+    fprintf( out, "#ifdef QT_THREAD_SUPPORT\n    if (qt_sharedMetaObjectMutex) qt_sharedMetaObjectMutex->unlock();\n#endif // QT_THREAD_SUPPORT\n" );
     fprintf( out, "    return metaObj;\n}\n" );
 
 //
diff --git a/src/moc/moc_yacc.cpp b/src/moc/moc_yacc.cpp
index b30fa23..cb307e6 100644
--- a/src/moc/moc_yacc.cpp
+++ b/src/moc/moc_yacc.cpp
@@ -5812,7 +5812,9 @@ void generateClass()		      // generate C++ source code for a class
 // Generate staticMetaObject member function
 //
     fprintf( out, "QMetaObject* %s::staticMetaObject()\n{\n", (const char*)qualifiedClassName() );
-    fprintf( out, "    if ( metaObj )\n\treturn metaObj;\n" );
+    fprintf( out, "    if ( metaObj ) {\n\treturn metaObj;\n}\n" );
+    fprintf( out, "#ifdef QT_THREAD_SUPPORT\n    if (qt_sharedMetaObjectMutex) qt_sharedMetaObjectMutex->lock();\n" );
+    fprintf( out, "    if ( metaObj ) {\n\tif (qt_sharedMetaObjectMutex) qt_sharedMetaObjectMutex->unlock();\n\treturn metaObj;\n    }\n#endif // QT_THREAD_SUPPORT\n" );
     if ( isQObject )
 	fprintf( out, "    QMetaObject* parentObject = staticQtMetaObject();\n" );
     else if ( !g->superClassName.isEmpty() )
@@ -5882,6 +5884,7 @@ void generateClass()		      // generate C++ source code for a class
 // Setup cleanup handler and return meta object
 //
     fprintf( out, "    cleanUp_%s.setMetaObject( metaObj );\n", cleanup.data() );
+    fprintf( out, "#ifdef QT_THREAD_SUPPORT\n    if (qt_sharedMetaObjectMutex) qt_sharedMetaObjectMutex->unlock();\n#endif // QT_THREAD_SUPPORT\n" );
     fprintf( out, "    return metaObj;\n}\n" );
 
 //
diff --git a/src/styles/qcommonstyle.cpp b/src/styles/qcommonstyle.cpp
index 0ab98b4..c7382d2 100644
--- a/src/styles/qcommonstyle.cpp
+++ b/src/styles/qcommonstyle.cpp
@@ -42,6 +42,7 @@
 
 #ifndef QT_NO_STYLE
 
+#include "qmutex.h"
 #include "qmenubar.h"
 #include "qapplication.h"
 #include "qpainter.h"
@@ -2782,6 +2783,9 @@ int QCommonStyle::pixelMetric(PixelMetric m, const QStyleControlElementData &ceD
 		ret = QMAX( QFontMetrics(ceData.font).lineSpacing(), 18 );
 	    }
 	}
+	else {
+		ret = 0;
+	}
 	break; }
     case PM_ScrollBarSliderMin:
 	ret = 9;
@@ -2853,12 +2857,15 @@ int QCommonStyle::pixelMetric(PixelMetric m, const QStyleControlElementData &ceD
 	    int thickness = pixelMetric( PM_SliderControlThickness, ceData, elementFlags, widget );
 	    int ticks = ceData.tickMarkSetting;
 
-	    if ( ticks == QSlider::Both )
+	    if ( ticks == QSlider::Both ) {
 		ret = (space - thickness) / 2;
-	    else if ( ticks == QSlider::Above )
+	    }
+	    else if ( ticks == QSlider::Above ) {
 		ret = space - thickness;
-	    else
+	    }
+	    else {
 		ret = 0;
+	    }
 	    break;
 	}
 
diff --git a/src/tools/qshared.h b/src/tools/qshared.h
index 290592c..7fe2593 100644
--- a/src/tools/qshared.h
+++ b/src/tools/qshared.h
@@ -45,7 +45,6 @@
 #include "qglobal.h"
 #endif // QT_H
 
-
 struct Q_EXPORT QShared
 {
     QShared() : count( 1 ) { }
diff --git a/src/tools/qstring.cpp b/src/tools/qstring.cpp
index 8717f6a..0630cd3 100644
--- a/src/tools/qstring.cpp
+++ b/src/tools/qstring.cpp
@@ -87,6 +87,12 @@
 #define ULLONG_MAX Q_UINT64_C(18446744073709551615)
 #endif
 
+#ifdef QT_THREAD_SUPPORT
+#include "qmutex.h"
+#endif // QT_THREAD_SUPPORT
+
+extern QMutex *qt_sharedStringMutex;
+
 static int ucstrcmp( const QString &as, const QString &bs )
 {
     const QChar *a = as.unicode();
@@ -1033,12 +1039,54 @@ static inline bool format(QChar::Decomposition tag, QString & str,
 } // format()
 #endif
 
+QStringData::QStringData() : QShared(),
+	unicode(0),
+	ascii(0),
+	len(0),
+	issimpletext(TRUE),
+	maxl(0),
+	islatin1(FALSE),
+	security_unpaged(FALSE) {
+#ifdef QT_THREAD_SUPPORT
+	mutex = new QMutex( TRUE );
+	mutex->lock();
+#endif // QT_THREAD_SUPPORT
+	ref();
+#ifdef QT_THREAD_SUPPORT
+	mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+}
+
+QStringData::QStringData(QChar *u, uint l, uint m) : QShared(),
+	unicode(u),
+	ascii(0),
+	len(l),
+	issimpletext(FALSE),
+	maxl(m),
+	islatin1(FALSE),
+	security_unpaged(FALSE) {
+#ifdef QT_THREAD_SUPPORT
+	mutex = new QMutex( TRUE );
+#endif // QT_THREAD_SUPPORT
+}
+
 QStringData::~QStringData() {
-    if ( unicode ) delete[] ((char*)unicode);
-    if ( ascii && security_unpaged ) {
-	munlock(ascii, LINUX_MEMLOCK_LIMIT_BYTES);
-    }
-    if ( ascii ) delete[] ascii;
+	if ( unicode ) delete[] ((char*)unicode);
+	if ( ascii && security_unpaged ) {
+		munlock(ascii, LINUX_MEMLOCK_LIMIT_BYTES);
+	}
+	if ( ascii ) delete[] ascii;
+#ifdef QT_THREAD_SUPPORT
+	if ( mutex ) delete mutex;
+#endif // QT_THREAD_SUPPORT
+}
+
+void QStringData::setDirty() {
+	if ( ascii ) {
+		delete [] ascii;
+		ascii = 0;
+	}
+	issimpletext = FALSE;
 }
 
 /*
@@ -1194,27 +1242,30 @@ QChar* QString::latin1ToUnicode( const char *str, uint* len, uint maxlen )
     return result;
 }
 
-static QChar* internalLatin1ToUnicode( const char *str, uint* len,
-				      uint maxlen = (uint)-1 )
+static QChar* internalLatin1ToUnicode( const char *str, uint* len, uint maxlen = (uint)-1 )
 {
     QChar* result = 0;
     uint l = 0;
     if ( str ) {
 	if ( maxlen != (uint)-1 ) {
-	    while ( l < maxlen && str[l] )
+	    while ( l < maxlen && str[l] ) {
 		l++;
-	} else {
+	    }
+	}
+	else {
 	    // Faster?
 	    l = int(strlen( str ));
 	}
 	QChar *uc = QT_ALLOC_QCHAR_VEC( l );
 	result = uc;
 	uint i = l;
-	while ( i-- )
+	while ( i-- ) {
 	    *uc++ = *str++;
+	}
     }
-    if ( len )
+    if ( len ) {
 	*len = l;
+    }
     return result;
 }
 
@@ -1395,11 +1446,26 @@ QT_STATIC_CONST_IMPL QChar QChar::nbsp((ushort)0x00a0);
 
 QStringData* QString::makeSharedNull()
 {
+#ifdef QT_THREAD_SUPPORT
+    if (qt_sharedStringMutex) qt_sharedStringMutex->lock();
+#endif // QT_THREAD_SUPPORT
+
+    if (QString::shared_null) {
+#ifdef QT_THREAD_SUPPORT
+	if (qt_sharedStringMutex) qt_sharedStringMutex->unlock();
+#endif // QT_THREAD_SUPPORT
+	return QString::shared_null;
+    }
+
     QString::shared_null = new QStringData;
 #if defined( Q_OS_MAC ) || defined(Q_OS_SOLARIS) || defined(Q_OS_HPUX) || defined(Q_OS_AIX)
     QString *that = const_cast<QString *>(&QString::null);
     that->d = QString::shared_null;
 #endif
+
+#ifdef QT_THREAD_SUPPORT
+    if (qt_sharedStringMutex) qt_sharedStringMutex->unlock();
+#endif // QT_THREAD_SUPPORT
     return QString::shared_null;
 }
 
@@ -1412,6 +1478,24 @@ QStringData* QString::makeSharedNull()
     \sa isNull()
 */
 
+// FIXME
+// Original Qt3 code stated that there is
+// "No safe way to pre-init shared_null on ALL compilers/linkers"
+// Is this still true?
+
+QString::QString() :
+    d(0)
+{
+	d = shared_null ? shared_null : makeSharedNull();
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+	d->ref();
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+}
+
 /*!
     Constructs a string of length one, containing the character \a ch.
 */
@@ -1428,7 +1512,15 @@ QString::QString( QChar ch )
 QString::QString( const QString &s ) :
     d(s.d)
 {
+#ifdef QT_THREAD_SUPPORT
+    d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+
     d->ref();
+
+#ifdef QT_THREAD_SUPPORT
+    d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
 }
 
 /*!
@@ -1451,7 +1543,13 @@ QString::QString( int size, bool /*dummy*/ )
 	d = new QStringData( uc, 0, l );
     } else {
 	d = shared_null ? shared_null : (shared_null=new QStringData);
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
 	d->ref();
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
     }
 }
 
@@ -1493,11 +1591,19 @@ QString::QString( const QChar* unicode, uint length )
 {
     if ( !unicode && !length ) {
 	d = shared_null ? shared_null : makeSharedNull();
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
 	d->ref();
-    } else {
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+    }
+    else {
 	QChar* uc = QT_ALLOC_QCHAR_VEC( length );
-	if ( unicode )
+	if ( unicode ) {
 	    memcpy(uc, unicode, length*sizeof(QChar));
+	}
 	d = new QStringData(uc,unicode ? length : 0,length);
     }
 }
@@ -1556,6 +1662,10 @@ QString::QString( const std::string &str )
 }
 #endif
 
+QString::QString( QStringData* dd, bool /* dummy */ ) {
+	d = dd;
+}
+
 /*!
     \fn QString::~QString()
 
@@ -1563,6 +1673,31 @@ QString::QString( const std::string &str )
     last reference to the string.
 */
 
+QString::~QString()
+{
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+	if ( d->deref() ) {
+		if ( d != shared_null ) {
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+			d->deleteSelf();
+		}
+		else {
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+		}
+	}
+	else {
+#ifdef QT_THREAD_SUPPORT
+		d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+	}
+}
+
 
 /*!
     Deallocates any space reserved solely by this QString.
@@ -1580,11 +1715,25 @@ void QString::real_detach()
 
 void QString::deref()
 {
-    if ( d && d->deref() ) {
-	if ( d != shared_null )
-	    delete d;
-	d = 0;
-    }
+	if ( d ) {
+#ifdef QT_THREAD_SUPPORT
+		d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+		if ( d->deref() ) {
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+			if ( d != shared_null ) {
+				delete d;
+			}
+			d = 0;
+		}
+		else {
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+		}
+	}
 }
 
 void QStringData::deleteSelf()
@@ -1624,9 +1773,16 @@ void QStringData::deleteSelf()
 */
 QString &QString::operator=( const QString &s )
 {
+#ifdef QT_THREAD_SUPPORT
+    s.d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
     s.d->ref();
+#ifdef QT_THREAD_SUPPORT
+    s.d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
     deref();
     d = s.d;
+
     return *this;
 }
 
@@ -1730,6 +1886,10 @@ void QString::truncate( uint newLen )
 */
 void QString::setLength( uint newLen )
 {
+#ifdef QT_THREAD_SUPPORT
+    d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+
     if ( d->count != 1 || newLen > d->maxl ||
 	 ( newLen * 4 < d->maxl && d->maxl > 4 ) ) {
 	// detach, grow or shrink
@@ -1739,12 +1899,24 @@ void QString::setLength( uint newLen )
 	    uint len = QMIN( d->len, newLen );
 	    memcpy( nd, d->unicode, sizeof(QChar) * len );
 	    bool unpaged = d->security_unpaged;
+#ifdef QT_THREAD_SUPPORT
+	    d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
 	    deref();
 	    d = new QStringData( nd, newLen, newMax );
 	    setSecurityUnPaged(unpaged);
 	}
-    } else {
+	else {
+#ifdef QT_THREAD_SUPPORT
+	    d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+	}
+    }
+    else {
 	d->len = newLen;
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
 	d->setDirty();
     }
 }
@@ -1830,10 +2002,21 @@ void QString::squeeze()
 */
 void QString::grow( uint newLen )
 {
+#ifdef QT_THREAD_SUPPORT
+    d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+
     if ( d->count != 1 || newLen > d->maxl ) {
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
 	setLength( newLen );
-    } else {
+    }
+    else {
 	d->len = newLen;
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
 	d->setDirty();
     }
 }
@@ -5868,13 +6051,15 @@ static QChar *addOne(QChar *qch, QString &str)
 */
 QString QString::fromUtf8( const char* utf8, int len )
 {
-    if ( !utf8 )
+    if ( !utf8 ) {
 	return QString::null;
+    }
 
     int slen = 0;
     if (len >= 0) {
-	while (slen < len && utf8[slen])
+	while (slen < len && utf8[slen]) {
 		slen++;
+	}
     } else {
         slen = int(strlen(utf8));
     }
@@ -6012,10 +6197,13 @@ QString QString::fromLatin1( const char* chars, int len )
 {
     uint l;
     QChar *uc;
-    if ( len < 0 )
+    if ( len < 0 ) {
 	 len = -1;
+    }
     uc = internalLatin1ToUnicode( chars, &l, len );
-    return QString( new QStringData(uc, l, l), TRUE );
+    QString ret( new QStringData(uc, l, l), TRUE );
+
+    return ret;
 }
 
 /*!
@@ -6178,7 +6366,8 @@ QString QString::fromUcs2( const unsigned short *str )
 	    length++;
 	QChar* uc = QT_ALLOC_QCHAR_VEC( length );
 	memcpy( uc, str, length*sizeof(QChar) );
-	return QString( new QStringData( uc, length, length ), TRUE );
+	QString ret( new QStringData( uc, length, length ), TRUE );
+	return ret;
     }
 }
 
@@ -6225,6 +6414,25 @@ QString QString::fromUcs2( const unsigned short *str )
     \sa constref()
 */
 
+QChar& QString::ref(uint i) {
+#ifdef QT_THREAD_SUPPORT
+	d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+	if ( (d->count != 1) || (i >= d->len) ) {
+#ifdef QT_THREAD_SUPPORT
+		d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+		subat( i );
+	}
+	else {
+#ifdef QT_THREAD_SUPPORT
+		d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+	}
+	d->setDirty();
+	return d->unicode[i];
+}
+
 /*!
     \fn QChar QString::operator[]( int ) const
 
@@ -6300,27 +6508,48 @@ void QString::subat( uint i )
 
 QString& QString::setUnicode( const QChar *unicode, uint len )
 {
-    if ( len == 0 ) {                           // set to null string
-	if ( d != shared_null ) {               // beware of nullstring being set to nullstring
-	    deref();
-	    d = shared_null ? shared_null : makeSharedNull();
-	    d->ref();
+	if ( len == 0 ) {                       // set to null string
+		if ( d != shared_null ) {       // beware of nullstring being set to nullstring
+			deref();
+			d = shared_null ? shared_null : makeSharedNull();
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+			d->ref();
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+		}
 	}
-    } else if ( d->count != 1 || len > d->maxl ||
-		( len * 4 < d->maxl && d->maxl > 4 ) ) {
-	// detach, grown or shrink
-	uint newMax = computeNewMax( len );
-	QChar* nd = QT_ALLOC_QCHAR_VEC( newMax );
-	if ( unicode )
-	    memcpy( nd, unicode, sizeof(QChar)*len );
-	deref();
-	d = new QStringData( nd, len, newMax );
-    } else {
-	d->len = len;
-	d->setDirty();
-	if ( unicode )
-	    memcpy( d->unicode, unicode, sizeof(QChar)*len );
-    }
+	else {
+#ifdef QT_THREAD_SUPPORT
+		d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+		if ( d->count != 1 || len > d->maxl || ( len * 4 < d->maxl && d->maxl > 4 ) ) {
+			// detach, grown or shrink
+			uint newMax = computeNewMax( len );
+			QChar* nd = QT_ALLOC_QCHAR_VEC( newMax );
+			if ( unicode ) {
+				memcpy( nd, unicode, sizeof(QChar)*len );
+			}
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+			deref();
+			d = new QStringData( nd, len, newMax );
+		}
+		else {
+			d->len = len;
+#ifdef QT_THREAD_SUPPORT
+			d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
+			d->setDirty();
+			if ( unicode ) {
+				memcpy( d->unicode, unicode, sizeof(QChar)*len );
+			}
+		}
+	}
+
     return *this;
 }
 
@@ -7024,15 +7253,23 @@ QConstString::QConstString( const QChar* unicode, uint length ) :
 */
 QConstString::~QConstString()
 {
+#ifdef QT_THREAD_SUPPORT
+    d->mutex->lock();
+#endif // QT_THREAD_SUPPORT
+
     if ( d->count > 1 ) {
 	QChar* cp = QT_ALLOC_QCHAR_VEC( d->len );
 	memcpy( cp, d->unicode, d->len*sizeof(QChar) );
 	d->unicode = cp;
-    } else {
+    }
+    else {
 	d->unicode = 0;
     }
 
     // The original d->unicode is now unlinked.
+#ifdef QT_THREAD_SUPPORT
+    d->mutex->unlock();
+#endif // QT_THREAD_SUPPORT
 }
 
 /*!
diff --git a/src/tools/qstring.h b/src/tools/qstring.h
index 58830db..8715395 100644
--- a/src/tools/qstring.h
+++ b/src/tools/qstring.h
@@ -71,6 +71,7 @@
 class QRegExp;
 class QString;
 class QCharRef;
+class QMutex;
 template <class T> class QDeepCopy;
 
 class Q_EXPORT QChar {
@@ -359,22 +360,14 @@ inline bool operator>( QChar c1, QChar c2 ) { return !(c2>=c1); }
 
 // internal
 struct Q_EXPORT QStringData : public QShared {
-    QStringData() :
-        QShared(), unicode(0), ascii(0), len(0), issimpletext(TRUE), maxl(0), islatin1(FALSE), security_unpaged(FALSE) { ref(); }
-    QStringData(QChar *u, uint l, uint m) :
-        QShared(), unicode(u), ascii(0), len(l), issimpletext(FALSE), maxl(m), islatin1(FALSE), security_unpaged(FALSE) { }
+    QStringData();
+    QStringData(QChar *u, uint l, uint m);
     ~QStringData();
 
     void deleteSelf();
     QChar *unicode;
     char *ascii;
-    void setDirty() {
-	if ( ascii ) {
-	    delete [] ascii;
-	    ascii = 0;
-	}
-	issimpletext = FALSE;
-    }
+    void setDirty();
 #ifdef Q_OS_MAC9
     uint len;
 #else
@@ -390,6 +383,8 @@ struct Q_EXPORT QStringData : public QShared {
 
     bool security_unpaged : 1;
 
+    QMutex* mutex;
+
 private:
 #if defined(Q_DISABLE_COPY)
     QStringData( const QStringData& );
@@ -646,13 +641,7 @@ public:
 
     QChar constref(uint i) const
         { return at(i); }
-    QChar& ref(uint i)
-        { // Optimized for easy-inlining by simple compilers.
-            if ( d->count != 1 || i >= d->len )
-                subat( i );
-            d->setDirty();
-            return d->unicode[i];
-        }
+    QChar& ref(uint i);
 
     const QChar* unicode() const { return d->unicode; }
     const char* ascii() const;
@@ -747,7 +736,7 @@ private:
 
     friend class QConstString;
     friend class QTextStream;
-    QString( QStringData* dd, bool /* dummy */ ) : d(dd) { }
+    QString( QStringData* dd, bool /* dummy */ );
 
     // needed for QDeepCopy
     void detach();
@@ -839,25 +828,6 @@ Q_EXPORT QDataStream &operator>>( QDataStream &, QString & );
   QString inline functions
  *****************************************************************************/
 
-// These two move code into makeSharedNull() and deletesData()
-// to improve cache-coherence (and reduce code bloat), while
-// keeping the common cases fast.
-//
-// No safe way to pre-init shared_null on ALL compilers/linkers.
-inline QString::QString() :
-    d(shared_null ? shared_null : makeSharedNull())
-{
-    d->ref();
-}
-//
-inline QString::~QString()
-{
-    if ( d->deref() ) {
-        if ( d != shared_null )
-	    d->deleteSelf();
-    }
-}
-
 // needed for QDeepCopy
 inline void QString::detach()
 { real_detach(); }
diff --git a/src/tools/qthreadinstance_p.h b/src/tools/qthreadinstance_p.h
index 7580b25..34550a8 100644
--- a/src/tools/qthreadinstance_p.h
+++ b/src/tools/qthreadinstance_p.h
@@ -101,6 +101,7 @@ public:
 #endif // Q_OS_WIN32
 
     QEventLoop* eventLoop;
+    int cleanupType;
 };
 
 #endif // QT_THREAD_SUPPORT
diff --git a/tutorial/t15/main.cpp b/tutorial/t15/main.cpp
index 4c96083..61febaa 100644
--- a/tutorial/t15/main.cpp
+++ b/tutorial/t15/main.cpp
@@ -33,6 +33,8 @@ void WorkerObject::run()
 		eventLoop->processEvents(QEventLoop::AllEvents);
 	}
 
+	delete t;
+
 	eventLoop->exit(0);
 }