The container control sends the WM_CONTROL (in Container Controls) message with the CN_CONTEXTMENU notification code to its owner when the container receives a WM_CONTEXTMENU message.

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

param2
     PRECORDCORE  pRecord         /*  Pointer to the RECORDCORE structure. */