`XtStrings'
...........
You may find that linking X programs results in an error from the
linker that `XtStrings' is undefined, something like this:
gcc -o virmf ...
.../x11.c:130: undefined reference to `XtStrings'
This generally happens because of a mismatch between the X include
files with which you compiled and the X libraries with which you linked;
often, the include files are from MIT and the libraries from Sun.
The solution is to use the same X distribution for compilation and
linking. Probably `configure' was unable to guess the proper
directories from your installation. You can use the `configure'
options `--x-includes=PATH' and `--x-libraries=PATH' to explicitly
specify them.