/**
  * Load an icon for a supported project file.
  *
  * @param f the file to check
  * @return a nice icon if the file is known as a project file, otherwise a default one
  */
 public Icon getIcon(File f) {
   AbstractFilePersister persister =
       PersistenceManager.getInstance().getPersisterFromFileName(f.getName());
   if (persister != null && persister.hasAnIcon()) {
     return Argo.lookupIconResource("UmlNotation");
   } else {
     return null;
   }
 }