thanks, I didn't think it would be this simple to list all
var in _root.
the only issue remaining is the case where I have more than
one url passed on to my swf file, and how to distinguish which one
is the one to use, but that's not really feasible (and anyway I
can't think of a case where more than one var would be passed to
the swfs I work on, let alone populated with an url).