Can't get GDK+ to compile/install.

["John Lambert" <johnlambert eircom net>]

Just bought the book Developing Linux Applications with GTK+ and GDK.  The
GDK in looking for a file in the X11 directory called Intrinsic.h.  I have
Caldera linux and this h file is not to be found any where.  Could you
point me to a place to obtain an X11 directory that will satisfy GDK+ to
install.

Yours obliged John Lambert.