ResourceEdit is a REALbasic plugin that has been put to life for a couple of reasons. The first reason was to provide tools you can use to meaningfully implement a new class that comes with NavDialog Plugin. This new class is called NavCustomization, which allows you to add a DITL resource to a NavDialog window.
Navigation Services allows you to do this, and because Navigation belongs to the Human Interface Experience, it was almost imperative to implement ResourceEdit. In order to give the REALbasic programmer the necessary tools, a new plugin had to be created, which does several things.