Adding an MFC Message Handler
You can use the Properties window to add a message handler (a member function that handles Windows messages) to a class and map Windows messages to the message handler. You can also add an event handler for any dialog box control.
By using the Properties window to define message- and event-handling functions, you can automatically update the message-dispatch table (or message map) and your class header file.
Note
You can add a message handler to an ATL class using the Properties window; however, some results may vary. For more information, see the ATL topic Adding an ATL Message Handler.
See Also
Tasks
Adding a Member Function (Visual C++)
Adding a Member Variable (Visual C++)
Overriding a Virtual Function (Visual C++)
Reference
Navigating the Class Structure (Visual C++)