Index: /trunk/src/org/openstreetmap/josm/gui/preferences/PreferenceTabbedPane.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/preferences/PreferenceTabbedPane.java	(revision 5857)
+++ /trunk/src/org/openstreetmap/josm/gui/preferences/PreferenceTabbedPane.java	(revision 5858)
@@ -405,4 +405,6 @@
                     }
                 }
+            } else if (!(setting instanceof SubPreferenceSetting)) {
+                Main.warn("Ignoring preferences "+setting);
             }
         }