It is easy do develop jEdit plugins with Eclipse. Just add jEdit.jar to the classpath of the Eclipse project. Optimally with the sources set to the jEdit source, so it is also possible to browse the jEdit sources.

Now to start jEdit just create a new run configuration and start org.gjt.sp.jedit.jEdit as java application. To install the plugin you need to export the project as JAR archive and save it under ~/.jedit/jars. But this can also happen as an ant target which can be added to the projects builders, then everything happens automatically.

Yes, just run jEdit in a separte JVM with remote debugging enabled, set your breakpoints in Eclipse, then start a remote debugging session.

Step by step:

1. Create your plugin in Eclipse
2. Build the jar (probably using ant)
3. Copy the jar to your jEdit installation
4. Start jEdit with remote debugging enabled (see below)
5. Attach the Eclipse debugger (see below)

To run jedit with remote debugging enabled, I use the following command:
"java -agentlib:jdwp=transport=dt_socket,suspend=y,server=y,address=XXXX -jar jedit.jar"

where XXXX is any open port number you wish. The above invocation works for Sun's JDK 5.0. There's an alternate incantation for earlier releases. (See http://java.sun.com/j2se/1.5.0/docs/guide/jpda/conninv.html)

To start debugging in Eclipse, create a debug configuration by selecting "Run->Debug->Remote Java Application" and set the port number you used above. jEdit will start and then stop at your first breakpoint. On subsequent run-throughs, use F11 (Debug last launched) as a shortcut. (Note, I'm using Eclipse 3.1)

-Ed King