MFC

Finding good information on how to enable drag and drop for MFC applications is hard enough (why?). But just when you think you should have it working, you hit a very solid wall: UIPI (User Interface Privilege Isolation, a variant of UAC, User Account Control). Because of “security” reasons, UIPI disables drag and drop from medium integrity processes (Explorer) to high integrity (aka elevated) processes by filtering out most window messages, including those required for drag and drop. In essence drag and drop from Explorer to your elevated application does not work.

If you create a C++ project in Visual Studio and configure it to “Use MFC in a Shared DLL” (the default) you need to make sure the C runtime (CRT) and the MFC libraries are installed in the correct versions on the end user’s computer. That can be difficult.

This is a quick and dirty description of how to use radio buttons in MFC, written because I could not find this information in a single place on the web.