Reference Documentation for GEF4
Reference Documentation for Draw2d, GEF (MVC), and Zest
Reference documentation for Draw2d and GEF (MVC) 3.x as well as Zest 1.x is provided in form of the GEF Developer Guide, which can be found in the Eclipse Help (Zest 1.x documentation is included since Kepler, see Bug 394137 for details). It contains the respective Programmer's Guides as well as the API References (Javadoc) for the three components. There is also some "unofficial" Draw2d/GEF (MVC) documentation provided by Régis Lemaigre ( Part 1 & Part 2).