Index: trunk/src/org/openstreetmap/josm/gui/ExceptionDialogUtil.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/ExceptionDialogUtil.java	(revision 4539)
+++ trunk/src/org/openstreetmap/josm/gui/ExceptionDialogUtil.java	(revision 4540)
@@ -299,4 +299,20 @@
 
     /**
+     * Explains a {@see OsmApiException} which was thrown because of a
+     * bandwidth limit (HTTP 509)
+     *
+     * @param e the exception
+     */
+    public static void explainBandwidthLimitExceeded(OsmApiException e) {
+        HelpAwareOptionPane.showOptionDialog(
+                Main.parent,
+                ExceptionUtil.explainBandwidthLimitExceeded(e),
+                tr("Bandwidth Limit Exceeded"),
+                JOptionPane.ERROR_MESSAGE,
+                ht("/ErrorMessages#BandwidthLimit")
+        );
+    }
+
+    /**
      * Explains a {@see OsmApiException} with a generic error
      * message.
@@ -441,4 +457,7 @@
                 explainClientTimeout(oae);
                 return;
+            case 509:
+                explainBandwidthLimitExceeded(oae);
+                return;
             default:
                 explainGenericHttpException(oae);