/// set the value from a string constant
Report ParameterQObject::setFromString(const QString& s)
{
    Report r;
    try {
        // call the specialisation
        r += _setFromString(s);
        if( r.success() )
            emit updatedSelection();
    }
    catch( const Report& err ) {
        r += err;
    }
    catch( const QString& err ) {
        r.addErrorMessage(err);
    }
    return r;
}