idControl (LONG) - input
The setting varies with the value of the idContext parameter.
For MCHK_CLASSMSGINTEREST, it can be SMI_INTEREST, or SMI_NOINTEREST, or SMI_AUTODISPATCH.
For MCHK_MSGINTEREST, it can be SMI_INTEREST, or SMI_NOINTEREST, or SMI_RESET, or SMI_AUTODISPATCH.
For MCHK_MSGMODE, it can be SMD_DELAYED or SMD_IMMEDIATE.
For MCHK_SYNCHRONISATION, it can be SSM_SYNCHRONOUS, or SSM_ASYNCHRONOUS, or SSM_MIXED.