Disable PrefferedArrival or PrefferedDeparture properties

Hello everyone,

I need to use StopTime property with either PrefferdArrival or PrefferedDeparture properties. I ve searched how to disabled PrefferdArrival or PrefferedDeparture by code but couldn t find anything. Do you know if it is possible (I know it is in MapPoint application so I think there must be a way to do so in the MapPoint control) ?

Thanks,
Victor.