--- set80.c	Thu Oct  8 22:28:50 1998
+++ set80.c-chmou	Mon Dec 20 20:38:18 1999
@@ -104,8 +104,14 @@
 
 int main (int argc, char* argv[])
 {
+  char * retval;
   int c;
   bool restore_all_regs=FALSE;
+  retval = getenv("DISPLAY");
+
+  if (retval != NULL)
+  	  PERROR(("Don't run set80 under X-Windows\n"));
+
 
   CommandName = argv[0];