TK runs under TCL, there is nothing you do in TK that is independent from TCL.

While the questioner turns out to be using Tcl, there is also a Tk module on CPAN that bundles a modified Tk (called "pTk") that is not dependent on Tcl. There was some confusion here because the questioner did not mention that he was using Tcl::Tk and I assumed that he was using Tk.