Geoff Chappell - Software Analyst
The INotificationCB methods are (as ordered in the virtual function table after the IUnknown methods):
HRESULT Notify (ULONG, NOTIFYITEM *);
The one known purpose of the INotificationCB interface is to provide a callback function for the taskbar’s notification area. The interface is to be implemented by any component that wants to know about notification-area items. To register the callback function with a notification area, pass the address of the INotificationCB interface as the argument to the RegisterCallback method of the notification area’s ITrayNotify interface.
The INotificationCB interface is supported by EXPLORER version 6.00 and higher.
Though this interface dates from 2001, it was still not documented by Microsoft as late as the January 2007 edition of the Windows Vista Software Development Kit (SDK).