ObjectARX supports dynamic MFC linking. Using an extension DLL is also recommended. In order to use the Autodesk AdUi and AcUi MFC base classes, you must dynamically link your MFC ObjectARX application and make it an extension DLL.
For complete information about MFC, see the Microsoft online help and technical notes. In particular, see TN011 and TN033 for information about using MFC as part of a DLL, which is an important concept for ObjectARX.