The container control sends a WM_CONTROL (in Container Controls) message with the CN_EMPHASIS notification code to its owner whenever a container record's attributes change.

param1
     USHORT                 id                     /*  Container control ID. */
     USHORT                 CN_EMPHASIS            /*  Notification code. */

param2
     PNOTIFYRECORDEMPHASIS  pNotifyRecordEmphasis  /*  Pointer to the NOTIFYRECORDEMPHASIS structure. */