Index: /trunk/src/org/openstreetmap/josm/data/osm/event/DatasetEventManager.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/osm/event/DatasetEventManager.java	(revision 2624)
+++ /trunk/src/org/openstreetmap/josm/data/osm/event/DatasetEventManager.java	(revision 2625)
@@ -62,4 +62,7 @@
     }
 
+    /* --------------------------------------------------------------------------- */
+    /* interface LayerChangeListener                                               */
+    /* --------------------------------------------------------------------------- */
     public void activeLayerChange(Layer a, Layer b) {
         if (a != null && a instanceof OsmDataLayer) {
@@ -69,5 +72,7 @@
             ((OsmDataLayer)b).data.addDataSetListener(myListener);
         }
-        processDatasetEvent(new DataChangedEvent(Main.main.getEditLayer().data));
+        if (Main.main.getEditLayer() != null) {
+            processDatasetEvent(new DataChangedEvent(Main.main.getEditLayer().data));
+        }
     }
     public void layerRemoved(Layer a) {/* irrelevant in this context */}