winfo interps return an empty string on windows
platforms (works on Unix platforms). See also - for
instance - http://www.faqs.org/faqs/tcl-faq/tk/windows/
"winfo interps" and "send" are a powerful and
easy-to-use facility for inter-process comminication
that should be available also on windows - and are
necessary to allow porting Unix based applications to a
windows platform. Work-arounds (based on dde, comm) are
not a suffiently satisfactory solution. See also the
comment on bug 1011499.