The container control sends a WM_CONTROL (in Container Controls) message with the CN_REALLOCPSZ notification code to its owner whenever container text is edited. It is sent before the CN_ENDEDIT notification code is sent.
param1
USHORT id /* Container control ID. */
USHORT CN_REALLOCPSZ /* Notification code. */
param2
PCNREDITDATA pCnrEditData /* Pointer to the CNREDITDATA structure. */