code: public void addObservableListener(ObservableListener<String> listener)
  	{
  		DocumentListener adapter = new ObservableListenerAdapter(listener);
  		
  		// remember adapter so we can remove it in removeObservableListener
  		adaptersByListener.put(listener, adapter);
  
  		textComponent.getDocument().addDocumentListener(adapter);
  	}
docs: {@inheritDoc}