Index: src/org/openide/explorer/view/TreeViewCellEditor.java
===================================================================
RCS file: /cvs/openide/src/org/openide/explorer/view/TreeViewCellEditor.java,v
retrieving revision 1.31
diff -u -r1.31 TreeViewCellEditor.java
--- src/org/openide/explorer/view/TreeViewCellEditor.java	22 Mar 2002 17:58:35 -0000	1.31
+++ src/org/openide/explorer/view/TreeViewCellEditor.java	9 May 2002 15:01:00 -0000
@@ -93,7 +93,7 @@
                         em.annotate(exc, msg);
                     }
                         
-                    em.notify(exc);
+                    em.notify(ErrorManager.USER, exc);
                 }
             }
         }
Index: src/org/openide/loaders/Bundle.properties
===================================================================
RCS file: /cvs/openide/src/org/openide/loaders/Bundle.properties,v
retrieving revision 1.82
diff -u -r1.82 Bundle.properties
--- src/org/openide/loaders/Bundle.properties	15 Apr 2002 15:24:58 -0000	1.82
+++ src/org/openide/loaders/Bundle.properties	9 May 2002 15:01:00 -0000
@@ -221,4 +221,4 @@
 LBL_loader_display_name=Loader
 
 MSG_renameError=This object cannot be renamed from {0} to {1}.
-
+MSG_NotValidName=Cannot give {0} an empty name.
Index: src/org/openide/loaders/DataObject.java
===================================================================
RCS file: /cvs/openide/src/org/openide/loaders/DataObject.java,v
retrieving revision 1.71
diff -u -r1.71 DataObject.java
--- src/org/openide/loaders/DataObject.java	12 Apr 2002 13:16:31 -0000	1.71
+++ src/org/openide/loaders/DataObject.java	9 May 2002 15:01:00 -0000
@@ -22,6 +22,7 @@
 import java.beans.*;
 import java.io.*;
 import java.lang.reflect.InvocationTargetException;
+import java.text.MessageFormat;
 import java.util.Enumeration;
 import java.util.Set;
 import java.util.HashSet;
@@ -551,6 +552,13 @@
     * @exception IOException if an error occurs
     */
     public final void rename (final String name) throws IOException {
+        if (name != null && name.trim ().length ()==0) {
+            IllegalArgumentException iae = new IllegalArgumentException (this.getName ());
+            String msg = MessageFormat.format (NbBundle.getMessage (DataObject.class,
+                                  "MSG_NotValidName"), new String[] {getName ()}); // NOI18N
+            ErrorManager.getDefault ().annotate (iae, msg);
+            throw iae;
+        }
         String oldName;
         final FileObject[] files = new FileObject[2]; // [old, new]