Indicates which function will handle a custom-control notification message.
The notification code of the control.
The command ID.
The name of the message-handler function to which the command is mapped.
Control notification messages are those sent from a control to its parent window.
There should be exactly one ON_CONTROL macro statement in your message map for every control notification message that must be mapped to a message-handler function.
For more information and examples, see Message Handling and Mapping Topics.