On Plug-ins and Extensible Architectures
gManZboy writes "Developers who want a flexible, configurable, IDE have long preferred plug-in architectures such as Eclipse over what they might view as the bloated, monolithic alternatives. Ever wondered how it all works? Well, ACM Queue just posted an article by someone who has worked on Eclipse since its inception, Dorian Birsan. He gives a great explanation of the Eclipse architecture as well as a thorough analysis of things to watch out for when developing or working with pure plug-in architectures."
Adding0 0,suspend=n
-Xdebug -Xrunjdwp:transport=dt_socket,server=y,address=80
to the java command when you run the app you want to debug allows Eclipse (& others) to attach on port 8000 (of course you can choose any unused port number)
If you want to debug an applet while it's running in a browser, you can specify the same arguments in the applet control panel.