Tkx is small pure-perl module, which uses small Tcl module to connect to Tcl/Tk, which provides far more flexible GUI than perl/Tk.

Yes, you can use any GUI builder from Tcl/Tk and then use either Tkx or Tcl::Tk for further programming.

I use this approach now in all my Tk applications (although I do not actually use vtcl anymore, but I do mix pure-Tcl code with perl/Tk code).

So, welcome to the club!
Join mailing list tcltk-at-perl.org!
(this ML serves 3 CPAN modules: Tkx, Tcl::Tk and Tcl)