Hello fellow Grails Developers!

I was wondering if you could help me with what must be a very common issue. I have come from a world of Java and eclipse where JavaDocs and APIs are at your fingertips. Grails has some great features and plugins but I find their inner workings completely undescoverable and that makes me sad.

Take for example the excellent authentication plugin, I set this up using the brief but accurate doc. Now I'm in eclipse with STS and I'm staring at a method;

applicationContext.authenticationService.filterRequest(
request, response, "${request.contextPath}/authentication/index" )

Which is throwing an exception;

2010-05-01 01:17:07,292 [http-8080-1] ERROR [/grailsapp].[default]  - Servlet.service() for servlet default threw exception
java.lang.IllegalStateException
    at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:407)
    at javax.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:118)
    at org.codehaus.groovy.grails.web.sitemesh.GrailsPageResponseWrapper.sendError(GrailsPageResponseWrapper.java:91)

And I have no idea where to start. I would love to have eclipse link to the source but there must be other manageable alternatives too as I know some people use TextMate or vim for development, they can't all have discovered the APIs for the plugins through trial and error!?! Is there any way of making the core Grails API more accessible / searchable? Autocomplete also doesn't seem to work for me in eclipse so if anyone has this working that would be ideal (It's an extension of the same question really).

What's your approach? (Please don't say intelliJ, I can't afford it) I'm sure it's obvious and I'm just missing it, please put me out of my misery!

Thanks in advance,

Gav