private String calculateText(QuestionData data) {
   String value = "";
   Expression expr = data.evaluateValue(questionProperties.getValuesTable());
   if (expr != null) {
     value = expr.toString();
   }
   return value;
 }
 public JPanel drawQuestion(ID id, String label, boolean editable) {
   QuestionData data = questionProperties.questionData(id);
   boolean visibility = data.evaluateVisibility(questionProperties.getValuesTable());
   JTextField textField = createTextField(id, editable, data);
   return generatePanel(id, label, visibility, textField);
 }