In Visual C++ you will need to tell the compiler where to find the FLTK header files. This can be done by selecting "Settings" from the "Project" menu and then changing the "Preprocessor" settings under the "C/C++" tab. Similarly, you will need to add the FLTK library to the "Link" settings.
You can build your Microsoft Windows applications as Console or WIN32 applications. If you want to use the standard C main() function as the entry point, FLTK includes a WinMain() function that will call your main() function for you.
Note: The Visual C++ 5.0 optimizer is known to cause problems with many programs. We only recommend using the "Favor Small Code" optimization setting. The Visual C++ 6.0 optimizer seems to be much better and can be used with the "optimized for speed" setting.