diff --git a/src/tools/qstring.cpp b/src/tools/qstring.cpp
index 014dc23..7f246fa 100644
--- a/src/tools/qstring.cpp
+++ b/src/tools/qstring.cpp
@@ -44,6 +44,11 @@
 #undef QT_NO_CAST_ASCII
 #endif
 
+// WARNING
+// When MAKE_QSTRING_THREAD_SAFE is defined, overall Qt3 performance suffers badly!
+// QString is thread unsafe in many other areas; perhaps this option is not even useful?
+// #define MAKE_QSTRING_THREAD_SAFE 1
+
 #include "qstring.h"
 #include "qregexp.h"
 #include "qdatastream.h"
@@ -87,9 +92,9 @@
 #define ULLONG_MAX Q_UINT64_C(18446744073709551615)
 #endif
 
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 #include "qmutex.h"
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 
 extern QMutex *qt_sharedStringMutex;
 
@@ -1047,9 +1052,9 @@ QStringData::QStringData() : QShared(),
 	maxl(0),
 	islatin1(FALSE),
 	security_unpaged(FALSE) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	mutex = new QMutex(FALSE);
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	ref();
 }
 
@@ -1061,9 +1066,9 @@ QStringData::QStringData(QChar *u, uint l, uint m) : QShared(),
 	maxl(m),
 	islatin1(FALSE),
 	security_unpaged(FALSE) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	mutex = new QMutex(FALSE);
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 }
 
 QStringData::~QStringData() {
@@ -1076,12 +1081,12 @@ QStringData::~QStringData() {
 	if ( ascii ) {
 		delete[] ascii;
 	}
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	if ( mutex ) {
 		delete mutex;
 		mutex = NULL;
 	}
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 }
 
 void QStringData::setDirty() {
@@ -1449,14 +1454,14 @@ QT_STATIC_CONST_IMPL QChar QChar::nbsp((ushort)0x00a0);
 
 QStringData* QString::makeSharedNull()
 {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
     if (qt_sharedStringMutex) qt_sharedStringMutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 
     if (QString::shared_null) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	if (qt_sharedStringMutex) qt_sharedStringMutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	return QString::shared_null;
     }
 
@@ -1466,9 +1471,9 @@ QStringData* QString::makeSharedNull()
     that->d = QString::shared_null;
 #endif
 
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
     if (qt_sharedStringMutex) qt_sharedStringMutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
     return QString::shared_null;
 }
 
@@ -1509,13 +1514,13 @@ QString::QString( const QString &s ) :
     d(s.d)
 {
     if (d != shared_null) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
         d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
         d->ref();
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
         d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
     }
 }
 
@@ -1668,20 +1673,20 @@ QString::~QString()
 		return;
 	}
 
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	if ( d->deref() ) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 		d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 		d->deleteSelf();
 		d = NULL;
 	}
 	else {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 		d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	}
 }
 
@@ -1703,22 +1708,22 @@ void QString::real_detach()
 void QString::deref()
 {
 	if ( d && (d != shared_null) ) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 		d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 		if ( d->deref() ) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 			d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 			if ( d != shared_null ) {
 				delete d;
 			}
 			d = 0;
 		}
 		else {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 			d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 		}
 	}
 }
@@ -1761,13 +1766,13 @@ void QStringData::deleteSelf()
 QString &QString::operator=( const QString &s )
 {
     if (s.d != shared_null) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
         s.d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
         s.d->ref();
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
         s.d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
     }
     deref();
     d = s.d;
@@ -1875,9 +1880,9 @@ void QString::truncate( uint newLen )
 */
 void QString::setLength( uint newLen )
 {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
     d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 
     if ( d->count != 1 || newLen > d->maxl ||
 	 ( newLen * 4 < d->maxl && d->maxl > 4 ) ) {
@@ -1888,24 +1893,24 @@ 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
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	    d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	    deref();
 	    d = new QStringData( nd, newLen, newMax );
 	    setSecurityUnPaged(unpaged);
 	}
 	else {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	    d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	}
     }
     else {
 	d->len = newLen;
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	d->setDirty();
     }
 }
@@ -1991,21 +1996,21 @@ void QString::squeeze()
 */
 void QString::grow( uint newLen )
 {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
     d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 
     if ( d->count != 1 || newLen > d->maxl ) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	setLength( newLen );
     }
     else {
 	d->len = newLen;
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	d->setDirty();
     }
 }
@@ -6404,19 +6409,19 @@ QString QString::fromUcs2( const unsigned short *str )
 */
 
 QChar& QString::ref(uint i) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 	d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	if ( (d->count != 1) || (i >= d->len) ) {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 		d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 		subat( i );
 	}
 	else {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 		d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 	}
 	d->setDirty();
 	return d->unicode[i];
@@ -6504,9 +6509,9 @@ QString& QString::setUnicode( const QChar *unicode, uint len )
 		}
 	}
 	else {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 		d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 		if ( d->count != 1 || len > d->maxl || ( len * 4 < d->maxl && d->maxl > 4 ) ) {
 			// detach, grown or shrink
 			uint newMax = computeNewMax( len );
@@ -6514,17 +6519,17 @@ QString& QString::setUnicode( const QChar *unicode, uint len )
 			if ( unicode ) {
 				memcpy( nd, unicode, sizeof(QChar)*len );
 			}
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 			d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 			deref();
 			d = new QStringData( nd, len, newMax );
 		}
 		else {
 			d->len = len;
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
 			d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 			d->setDirty();
 			if ( unicode ) {
 				memcpy( d->unicode, unicode, sizeof(QChar)*len );
@@ -7235,9 +7240,9 @@ QConstString::QConstString( const QChar* unicode, uint length ) :
 */
 QConstString::~QConstString()
 {
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
     d->mutex->lock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 
     if ( d->count > 1 ) {
 	QChar* cp = QT_ALLOC_QCHAR_VEC( d->len );
@@ -7249,9 +7254,9 @@ QConstString::~QConstString()
     }
 
     // The original d->unicode is now unlinked.
-#ifdef QT_THREAD_SUPPORT
+#if defined(QT_THREAD_SUPPORT) && defined(MAKE_QSTRING_THREAD_SAFE)
     d->mutex->unlock();
-#endif // QT_THREAD_SUPPORT
+#endif // QT_THREAD_SUPPORT && MAKE_QSTRING_THREAD_SAFE
 }
 
 /*!