I'm not sure if you can get multiple files from that widget.
However, you can "roll your own" without too much trouble by creating
a listbox which you fill with all the entries from a directory. Tix
has something that does this automatically. You can set your listbox to
allow multiple selections and they will be returned in a list when you
request the selected items from the listbox widget. Hope this helps.
Jim

-- 
James C Moore, Ph.D.
Principal, URS Technologies, LLC 
ph: 614-540-8041, jmoore@qn.net