No technical expert advice can be found here ;)

When creating a new WebApplication with GWT SDK 2.0.3 and App Engine SDK 1.3.3 in eclipse using the Instantiations WindowBuilder Pro or GWT Designer, the following error occors when trying to launch the “GWT application” (google calls this “Development Mode”).

Exception in thread “main” java.lang.NoSuchMethodError: org.mortbay.thread.Timeout.<init>(Ljava/lang/Object;)V
at org.mortbay.io.nio.SelectorManager$SelectSet.<init>(SelectorManager.java:306)
at org.mortbay.io.nio.SelectorManager.doStart(SelectorManager.java:223)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at org.mortbay.jetty.nio.SelectChannelConnector.doStart(SelectChannelConnector.java:303)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at org.mortbay.jetty.Server.doStart(Server.java:233)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:543)
at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:421)
at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1035)
at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:783)
at com.google.gwt.dev.DevMode.main(DevMode.java:275)

I could not figure out what is happening and why this exception is raised, but I found a workaround for this:

Instead of using the App Engine SDK 1.3.3 on creation of the new Web Application Project, select the App Engine SDK 1.3.1. Create the new project, then right-click the project-folder and select the Properties. In Google>App Engine you can now switch from App Engine 1.3.1 to App Engine 1.3.3 and your project will run cleanly under the new engine.

select new appengine in the properties