I think it would be interesting a new exceptions handling method: use case exceptions handling.

Imagine this scenario: I've got a use case object that throws a Runtime exception when it fails:

    public void createNewAccount() {
        if(useIsVerySilly()) {
             throw new UserIsVerySillyException();
        }
    }

And UserIsVerySillyException:

public class UserIsVerySillyException extends RuntimeException {

}

I don't want pages.xml traps this exception. I want current page .pages.xml navigation files capture it, to show a beautiful bundled message on it.

myusecasepage.page.xml should be:

     <exception class="org.test.UserIsVerySillyException">
          <redirect view-id="#{facesContext.externalContext.requestServletPath}">
               <message>#{messages['user_very_silly']}</message>
          </redirect>
     </exception>

So, basically, to trap exceptions in the same page they are generated.