public void addListener(Listener aListener){
  if (aListener == null)   return;
  if (hexEditControl == null) {
    if (listOfStatusChangedListeners == null)     listOfStatusChangedListeners=new ArrayList<>();
    listOfStatusChangedListeners.add(aListener);
  }
 else {
    hexEditControl.addListener(SWT.Modify,aListener);
  }
}

public void addListener ( Listener aListener ) { if ( aListener == null ) return ; if ( hexEditControl == null ) { if ( listOfStatusChangedListeners == null ) listOfStatusChangedListeners = new ArrayList < > ( ) ; listOfStatusChangedListeners . add ( aListener ) ; } else { hexEditControl . addListener ( SWT . Modify , aListener ) ; } }
add a listener to changes of the ' dirty ' , ' insert / overwrite ' , ' selection ' and ' canundo / canredo ' status
