NIF_REALTIME top-level constant Null safety
Windows Vista and later. If the balloon notification cannot be displayed immediately, discard it. Use this flag for notifications that represent real-time information which would be meaningless or misleading if displayed at a later time. For example, a message that states "Your telephone is ringing." NIF_REALTIME is meaningful only when combined with the NIF_INFO flag.
const NIF_REALTIME = 0x00000040;