Via jEdit Community, I’ve found a fix for the jEdit OS X package’s interface problems with the Java 1.4.1 update, but I think you need Apple Devtools installed: Go to the jEdit folder, Show Package Contents for the jEdit application, and change the Java version used to “1.3*” (not 1.3+). This will force jEdit to use the older JVM. Whatever that means, it worked; the icon is displaying properly again, and syntax formatting is back.