+# OSX is schizoid about who owns /usr/X11 (old) versus /opt/X11 (new), and (and
+# in some cases has installed dummy files in the former, other cases replaced
+# it with a link to the new location). This complicates the configure script.
+# Check for that pitfall, and recover using pkg-config
+#
+# If none of these are set, the configuration is almost certainly broken.
+if test -z "${X_CFLAGS}${X_PRE_LIBS}${X_LIBS}${X_EXTRA_LIBS}"
+then
+ CF_TRY_PKG_CONFIG(x11,,[AC_MSG_WARN(unable to find X11 library)])
+ CF_TRY_PKG_CONFIG(ice,,[AC_MSG_WARN(unable to find ICE library)])
+ CF_TRY_PKG_CONFIG(sm,,[AC_MSG_WARN(unable to find SM library)])
+ CF_TRY_PKG_CONFIG(xt,,[AC_MSG_WARN(unable to find Xt library)])
+fi
+