Searching for the source of a method

In order to get a better idea of how the in_place_editor_field helper works I searched the api docs and viewed the source of the method from the api docs. I noticed that it calls in_place_editor which instantiates ::ActionView::Helpers::InstanceTag. InstanceTag unfortunately wasn't documented in the apis anywhere so I had to go to my ruby gems directory and search the text of all my ruby files to find it. Is this typically how you would go about locating something that isn't documented? I miss just hitting F3 in eclipse for my Java code.

So after I located the class in form_helper.rb I wanted to figure out what the value method does but I'm not sure how to go about locating the source for the value method of self.class.value(object, @method_name). Any ideas?