>    Do both of them have to do it, or just one of them? Perhaps a utility
>    library routine should be written to do the job...
> 
> xdm has to do it also....

XDM already has a general and configurable way (shell scripts) to do this.

There's little point in hard-coding in C what can be done in those
shell scripts.  "if you're using XDM, there's no problem, even now."

cgd