diff -r 56cd8111b7f7 -r 41300fa6a67c src/plugins/graphicssystems/trace/qgraphicssystem_trace.cpp
--- a/src/plugins/graphicssystems/trace/qgraphicssystem_trace.cpp	Tue Jan 26 12:42:25 2010 +0200
+++ b/src/plugins/graphicssystems/trace/qgraphicssystem_trace.cpp	Tue Feb 02 00:43:10 2010 +0200
@@ -82,6 +82,7 @@
         QFile outputFile(QString(QLatin1String("qtgraphics-%0.trace")).arg(winId));
         if (outputFile.open(QIODevice::WriteOnly)) {
             QDataStream out(&outputFile);
+            out.writeBytes("qttrace", 7);
             out << *buffer << updates;
         }
         delete buffer;