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The tutorial you link to is for Tkx , a thin interface to Tcl, and its gui library toolkit, Tk
The tutorial you linked helps with the easy tcl syntax, like the Tkx docs, but as soon as you reach for the reference Tcl/Tk docs, you have to learn more Tcl syntax, so you can translate to perl.
Tcl::pTk, like Tkx, builds on Tcl but does it with Tk.pm compatible syntax, and takes the brilliant step and exposes the Tcl interpreter, so you can Eval Tcl code directly, no need to translate to perl at all
What Tk.pm has going for it, is years and years and years of use, many perl users, and many perl examples and cpan extensions
With ActiveState/ppm/Tkx you get, a certain set of Tcl/Tk widgets, Tcl::tkkit, great for embedding via par/perlapp/perl2exe. Its mostly a one-two-click operation, but you can't add more widgets.
If you go your own way :) you can install ActiveTcl (or other tcl distribution) and then install Tcl/Tcl::pTk||Tkx, you also get the ability, to install other widgets, like TIX, at the cost of two installations to manage, two path entries ... unless you decide which widgets you want and then build your own Tcl::kit equivalent
So yes, that tutorial you linked, is most excellent 2) one good tut.
If you stick to ActivePerl, Tkx is well supported by perl at minimal expense to the programmer, with an excellent but fixed set of widgets, with decent enough documentation.
SpecTCL fills the WYSYWIG designer role nicely, but the binaries are a tad dated, built around Tk 8.4 (ActivePerl deploys with the stable 8.5 , the current beta is 8.6)
Suitable for beginners? Yup, its a very good toehold, ought to get a beginner making short GUI programs in short order