/** Notify registered observers about big change in dataset */
 @Override
 public void performNotifyDataChanged() {
   if (mObservers != null) {
     synchronized (mObservers) {
       for (DownloadTableModel ob : mObservers) {
         ob.fireTableDataChanged();
       }
     }
   }
 }
 /**
  * Notify registered observers about change in one particular thread
  *
  * @param thread
  */
 @Override
 public void performNotifyDataChanged(FTPDownloadThread thread) {
   if (mObservers != null) {
     synchronized (mObservers) {
       int index = thread.getIndex();
       for (DownloadTableModel ob : mObservers) {
         ob.fireTableRowsUpdated(index, index);
       }
     }
   }
 }