Index: src/org/openstreetmap/josm/gui/dialogs/ValidatorDialog.java
===================================================================
--- src/org/openstreetmap/josm/gui/dialogs/ValidatorDialog.java	(revision 15602)
+++ src/org/openstreetmap/josm/gui/dialogs/ValidatorDialog.java	(working copy)
@@ -261,6 +261,7 @@
             updateSelection(ds.getAllSelected());
         }
         MainApplication.getLayerManager().addAndFireActiveLayerChangeListener(this);
+        validateAction.updateEnabledState();
 
     }