title: VisualStudio 2012 external includes visibility
body: <p>I have "source" and "include" folders which contain .cpp and .h files respectively for my project.
  I have them in the same directory as the project.In the project I include the content of both folders and in the properties add the "include" folder as additional include directory.The project compiles but I can't access any header which is not related to these files via intellisense.For example GL\glew.h headers are included and used in my headers but I can't see those in the headers list when typing #include. Once I create a .cpp file outside "include" or "source" folder all the rest of project includes become visible there again.What do I miss here? </p>