Index: /trunk/autoquest-htmlmonitor/src/main/java/de/ugoe/cs/autoquest/htmlmonitor/HtmlMonitorOutputWriter.java
===================================================================
--- /trunk/autoquest-htmlmonitor/src/main/java/de/ugoe/cs/autoquest/htmlmonitor/HtmlMonitorOutputWriter.java	(revision 1248)
+++ /trunk/autoquest-htmlmonitor/src/main/java/de/ugoe/cs/autoquest/htmlmonitor/HtmlMonitorOutputWriter.java	(revision 1249)
@@ -196,7 +196,7 @@
      */
     @Override
-    public void handleMessage(HtmlClientInfos clientInfos,
-                              HtmlGUIElement  guiStructure,
-                              HtmlEvent[]     events)
+    public synchronized void handleMessage(HtmlClientInfos clientInfos,
+                                           HtmlGUIElement  guiStructure,
+                                           HtmlEvent[]     events)
     {
         if (outputWriter == null) {