Thank you very much for the answer!!
According to information in this discussion topic http://community.jboss.org/message/597650?tstart=0
I have come across the Guvnor web editor (http://localhost:8080/designer/editor?profile=default&uuid=1234) for process design (which actually looks more powerfull than the Eclipse plugin).
Maybe there is anything similar for forms design??! Have not found by myself yet.