[R] Configuring R-2.5.0 for X11 on Red Hat WS 4 x86-64

[Bruce Foster]

I have been unable to configure R-2.5.0 for the X11 interface on Red 
Hat WS 4 x86-64 (AMD Opteron).

The configure script looks for XtToolkitInitialize in libXt, and does 
not find it because it's not in libXt (which is present, however).

I tried installing openmotif and openmotif-devel, and that is no help.

How do I configure the X11 interface under this situations?

Thanks,
Bruce