BCGControlBar Pro for MFC
void CBCGPAppointment::SetAllDay ( BOOL  bAllDay)

Sets an event to be "All day".

Use this function to make an event to be "All day" or regular. When an appointment becomes "All day", its start and end time are set to zero.

Parameters
bAllDayTRUE makes the event "All day"; FALSE makes the event to be regular.