code: private void handleChange(Object propertyId) {
  
          if (!m_saveBtn.isEnabled()) {
              m_saveBtn.setEnabled(true);
              m_saveExitBtn.setEnabled(true);
          }
          m_model.handleChange(propertyId);
  
      }
docs: Handle a value change.
  @param propertyId the column in which the value has changed.