Javascript documentation for things like ReportContext, ReportDesignHandle

I'm completely new to BIRT so bear with my potential ignorance here. In the "Integrating and Extending BIRT" guide book, I read the section regarding how a developer can write event handlers with Javascript. However, I couldn't find any documentation or reference as to what classes and what methods are available.

I know that in the Javascript editor in Designer, as soon as I type "reportContext.", it'll display the methods available. But what I'm looking for is the description of those methods, what they do, and what each parameter means.

Could someone knowledgeable points me in the right direction? Thanks in advance.