@Override
 public void focusLost(FocusEvent arg0) {
   state.putValue(computedQuestion.getIdent().getName(), control.getValue());
   setChanged();
   notifyObservers();
 }
 @Override
 public void actionPerformed(ActionEvent arg0) {
   state.putValue(computedQuestion.getIdent().getName(), control.getValue());
   setChanged();
   notifyObservers();
 }
 public void visit(ComputedQuestion computedQuestion, U context) {
   computedQuestion.getExpr().accept(this, context);
 }