Java Development Tools (JDT). This is part of a standard Eclipse
SDK install.
Graphical Editing Framework (GEF). This is an Eclipse project, and is
available here: http://www.eclipse.org/gef/.
GEF is currently distributed in 3 parts: a runtime, an SDK, and samples. It is
sufficient to install only the runtime if you don't plan to develop GEF applications
yourself.