Oh sure, I agree, flexibility for individual development styles and situations is important.
I'm not sure I made my question quite clear, though: Why are there two different places in the application where source file locations may be specified? ie, Project>>Properties>>Build Targets as well as Project>>Build Options>>Search Directories ...I expect I'm just not understanding the difference between these two dialogs, but they do seem like two things that ought to be unified into a single dialog.
By the way, I did try including full paths in my include statements (relative to main.cpp in the root folder of my project) but they still were not found (until I added src and include) to the Search Directories.