Tkx is an interface to Tk from Perl. Tk is a GUI toolkit tied to the Tcl language; Tkx provides a bridge to Tcl that allows Tk based applications to be written in Perl.
Description
The philosophy of Tkx is to provide a very thin wrapper on top of Tcl. You get exactly the behavior described in the Tcl/Tk documentation with no surprises added by the Perl layer.
The Tkx documentation describes the mapping between Tcl syntax and Perl syntax, but defers most everything else to the Tk documentation. You should consult the documentation for the version of Tk that you're using.
TkDocs provides tutorials for using Tk with examples using bindings from several languages, including Perl via Tkx.