Came for the beer, stayed for the Freedom

If you are not writing GLib or Gtk, you probably don’t need subdirectories in your header paths. I, too, do this often, and I think I’m ready to stop.
#include <gtk/gtk.h>
For example, in the above example, we include gtk/gtk.h. This was necessary (at least at one time) because we would have gtk/*, gdk/*, and possibly other [...]