Where the heck are the header files???

[Anton Vaaranmaa]

I'm trying to compile an KDE3.1 app. Configure complains that it can't find X. 
When I browse the dirs I find no ".h" files for X anywhere. I thought they 
were in XFree-libs, but the bzipped tarball does not have them either. 
Neither is there any XFree-devel package available, at least not available in 
the Cygwin setup. 

This is probably a FAQ, but please point me to the direction of where I can 
get hold of the headers.

Cheers,

-- 
Anton