The primary reason for JEditList 1.1 is Sun's change of packaging names for Swing.  You need to use the correct version of JEditList depending on which release of Sun's Swing or JDK products you use:
 

Swing 1.0.1 and 1.0.2	com.sun.java.swing	JEditList 1.0
Swing 1.1beta3 and final	javax.swing	JEditList 1.1
JDK 1.2beta3	java.awt.swing	no JEditList version available
JDK 1.2beta2 and beta4	com.sun.java.swing	JEditList 1.0
JDK 1.2final	javax.swing	JEditList 1.1

In addition, JEditList fixes a bug in JEditList 1.0 wherein using the popup menu prematurely updated the Undo remember buffer, losing the previous undo state.  This resulted in Undo not working from the popup menu but only from its command key equivalent.  This has now been fixed.