/// a current value is changed by property panel, the feature is displayed otherwise it is hidden
/// \param theOperation an operation which feature is to be displayed, it is nested create operation
/// \param isToDisplay a flag about the display or erase the feature
/// a current value is changed by property panel, the feature is displayed otherwise it is hidden
/// \param theOperation an operation which feature is to be displayed, it is nested create operation
/// \param isToDisplay a flag about the display or erase the feature