MFC has changed substantially since it shipped in Visual C++ Version 5.0. MFC 6.0 contains many new classes, new member functions, bug fixes, and enhancements. This document provides an overview of issues that could affect the porting of your MFC version 4.22 application to 6.0. For information on new classes and functionality for MFC 6.0, see What’s New for Visual C++ Version 6.0.
While the library has undergone some growth, you should be able to recompile your programs with the new library without any changes. Further, you should be able to install the MFC DLLs over old versions without recompiling programs which use the library. However, in some cases, changes in the library may cause problems when porting existing MFC application code. This document describes those changes which might be of interest to the developer.