static void registerListeners(final SwingOutputFieldRenderer renderer, final JTextField textField) {
        if(renderer != null && textField != null) {
            textField.getDocument().addDocumentListener(new DocumentListener() {
                public void insertUpdate(DocumentEvent event) {
                    send(event);
                    textField.setForeground(Color.black);
                }
                public void removeUpdate(DocumentEvent event) {
                    send(event);
                    textField.setForeground(Color.black);
                }
                public void changedUpdate(DocumentEvent event) {
                    send(event);
                }
                private void send(DocumentEvent event) {
                    Document doc = event.getDocument();
                    InputEditEvent evt = doc.getLength() == 0 ? InputEditEvent.EMPTY : InputEditEvent.FULL;
                    renderer.notifyInputEditListeners(evt);
                }
            });

            textField.addFocusListener(new FocusAdapter() {
                public void focusLost(FocusEvent fe) {
                   textField.setForeground(Color.black);
                }
            });
        }
    }