GWT/Errai quickstarts don't work out of the box in JBDS, as the plain JBDS wouldn't compile the GWT stuff.

How to reproduce:

0. Read the quickstart README
1. Start JBDS
2. import jboss-as-helloworld-errai quickstart as a maven project
3. Run as -> run on server, select an AS7/EAP6 instance
4. Notice that the deployed application doesn't work

The missing step is installing a GWT plugin and using the

Google -> Web toolkit settings ... to enable GWT
and
Google -> GWT Compile
to generate the client-side.

The missing step should be mentioned in the README files somewhere.