why do I have to install xfree86 ?

Why is it that the deps for gtk2 include XFree86? I have installed X11.app and X11SDK from the latest release of xcode from the Apple website. Is there a way that I can get it to use Apple's X11? -ajm ps: running 10.4.8, intel, x11 1.1.3, xcode 2.4.1 and darwinports 1.3.2