DWR 2 Good, DWR 3 BAD, Very-Very Bad

Lost time last few days messing with DWR 3, getting some exception:

failed dwr-invoker java.lang.NoClassDefFoundError: Could not initialize class com.google.apphosting.runtime.security.shared.stub.javax.swing.event.EventListenerList

me This was a problem in DWR 3.  Read a post on Google AppEngine for Java that mentioned a problem with DWR 3 and suggested that DWR 2 was ok.  So I went back to DWR 2 and all was well :-)