Index: trunk/src/org/openstreetmap/josm/gui/preferences/advanced/AdvancedPreference.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/advanced/AdvancedPreference.java	(revision 4879)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/advanced/AdvancedPreference.java	(revision 4880)
@@ -83,4 +83,8 @@
         }
 
+        public Setting getDefaultValue() {
+            return defaultValue;
+        }
+
         public void setValue(Setting value) {
             this.value = value;
@@ -259,5 +263,15 @@
                 label.setFont(label.getFont().deriveFont(Font.BOLD));
             }
-            //label.setToolTipText("..."); TODO
+            val = pe.getDefaultValue().getValue();
+            if(val != null)
+            {
+                if(pe.isDefault()) {
+                    label.setToolTipText(tr("Current value is default."));
+                } else {
+                    label.setToolTipText(tr("Default value is ''{0}''.", val));
+                }
+            } else {
+                label.setToolTipText(tr("Default value currently unknown (setting has not been used yet)."));
+            }
             return label;
         }