Here's your starting point:

Perl/Tk

And a tip: DO NOT start by trying to apply Tk in your FTP program. FIRST read thru the Tk docs, a tutorial, etc. and develop a few small experimental programs to learn with.

There are a few good reasons to work that way, one of which is it will make it much easier to ask specific questions here without having to dump a mess of code and explain a bunch of irrelevant details ;)