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