The framework calls this member function to inform the parent window of a control that an event has occurred in the control or that the control requires some kind of information.
OnNotify processes the message map for control notification.
Override this member function in your derived class to handle the WM_NOTIFY message. An override will not process the message map unless the base class OnNotify is called.
For more information on the WM_NOTIFY message, see Technical Note 61 (TN061), ON_NOTIFY and WM_NOTIFY messages. You may also be interested the related topics described in Control Topics, and TN062, Message Reflection for Windows Controls.