GTK+ works with Perl. GTK+ works under Win32. But getting GTK with Perl under Win32 is a problem. Last I heard (3-6 months ago), GTK-Perl was still a no-go on Win32.
I'd look around for wxWindows, which should work with Perl under a lot more platforms than GTK+. My only gripe with this is that I really like Glade (GTK+ WYSIWYG GUI editor), and I haven't found an equivilent tool for wxWindows (I hate actually writing GUI code).
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I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer
Note: All code is untested, unless otherwise stated