Tracy, I just used .pdf as an example, for Run will launch the associated program of any extension, but I do not have or even know what is .xfdf, so I used one that I know, .pdf :)
But, if you can not use scripting, I do not know other way of doing it, sorry
Hugo
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges