If you are already a JDT UI developer, check out the Development Resources.
The project summary page contains some more information about eclipse.jdt.ui.
The JDT UI implements the user interface for the Java IDE. It provides several workbench contributions for viewing and manipulating Java code:
In addition to these workbench elements the following functions are provided:
Take a look at the screen casts to see some JDT features like the new Java 7 support and code refactoring in action.
JDT UI contributes some plugins that are not part of the Eclipse SDK but can be downloaded from this update site:
Consult the plugin description pages for more information:
Pre 4.3 builds
If you are interested in participating in the development of the JDT UI component, check out the developer's mailing list: firstname.lastname@example.org. Chat with people there about your problems and interests, and find out what you can do to help.
If you have a background in the development of user interfaces, are interested in making the development and exploration of Java code fun, then don't hesitate to contact the JDT UI team. There is upcoming work in many areas like the Java editor or refactoring support. We need help for implementing many more refactorings. However be warned, the refactoring work is done in a strict test-first style, so get used to write tests before code!
For more detailed information, check out the Development Resources.