code: protected boolean isItemVisible(final T file) {
          return (isDir(file) ||
                  (mode == MODE_FILE || mode == MODE_FILE_AND_DIR) ||
                  (mode == MODE_NEW_FILE && allowExistingFile));
      }
docs: Cab be used by the list to determine whether a file should be displayed or not.
  Default behavior is to always display folders. If files can be selected,
  then files are also displayed. In case a new file is supposed to be selected,
  the {@link #allowExistingFile} determines if existing files are visible
  
  @param file either a directory or file.
  @return True if item should be visible in the picker, false otherwise