   Ever use multiple custom window classes?
  C++/WinOutside of common control classes, is there any reason to register more than one window class per thread/application?   
  Only if you wanted an additional window to use a different WndProc, default style, icon etc without having to set them yourself after window creation.I've never had to do it personally in 2 years of Windows development.   ;  If you implement user controls and can't base them off an existing control you'll have more of them.   