Index: trunk/src/org/openstreetmap/josm/tools/ListenerList.java
===================================================================
--- trunk/src/org/openstreetmap/josm/tools/ListenerList.java	(revision 10893)
+++ trunk/src/org/openstreetmap/josm/tools/ListenerList.java	(revision 10894)
@@ -150,7 +150,7 @@
             WeakListener<T> weakLink = iterator.next();
             T l = weakLink.listener.get();
-            if (l == null) {
-                iterator.remove();
-            } else {
+            if (l != null) {
+                // cleanup during add() should be enough to not cause memory leaks
+                // therefore, we ignore null listeners.
                 eventFirerer.fire(l);
             }