Editing a Message Handler
Once you have defined a message handler, you can go to the member function's definition to add or modify code.
To jump to a member function definition from the dialog editor, double-click a control for which a handler is already defined. This navigates you to the file in which the selected control's message handler is defined.
To jump to a member function definition from Class View, double-click the function name in Class View.
See also
Mapping Messages to Functions
Adding Functionality with Code Wizards
Adding a Class
Adding a Member Function
Adding a Member Variable
Overriding a Virtual Function
MFC Message Handler
Navigating the Class Structure