gui toolkits: the real story? (Tkinter, PyGTK, etc.)

[bramble]

What is the backstory to why Python includes Tk bindings, as opposed
to some other set of bindings?

I've written a few little Tkinter-based apps, and it's nice and
simple. I like it well enough. That said though, I keep feeling the
gravitational pull toward GTK+. I've been meaning to get the whole
glade+gtk+python thing happening with my own projects, as soon as time
allows. Is there resistance in the upper Python echelons to GTK
because of its LGPL licensing?

Reading Alex's Nutshell book, right off the bat he comments that "The
most popular Python GUI toolkit today is probably wxPython". But then
he goes on for 45 pages on Tkinter... Seems like he wanted to write
that chapter on wx instead...

WxWidgets, the last time I looked at it, seemed awfully like MS
Window's MFC. The licensing seemed vague at the time, and it looks
like wx contains an extra layer of GUI library, so I didn't spend any
real time on it. But, regardless, it seems to get good press among
python folk (I think I remember ESR noting how it was his GUI toolkit
of choice).

PyQt has had that issue (IIRC) about needing to pay for it for
commercial apps, so I can see how there might be resistance to it
being considered the "standard Python GUI toolkit".

So, it would seem to me that Tkinter *might* remain in Python proper,
but that I probably wouldn't see much effort put into it. Well, the
Python standard library docs tell a different story. There's stuff in
there about Tix, ScrolledText, turtle, and then the "other GUI
packages" doc page goes on about Python megawidgets (Tk-based) and
Tkinter3000 Widget Construction Kit (WCK). Wow. Looks like Tkinter is
still having serious support -- even though in that same doc at the
bottom notes, "PyGTK, PyQt, and wxPython, all have a modern look and
feel and far more widgets and better documentation than Tkinter."

So, that leaves me wondering, why is Tkinter still getting so much
focus in the Python standard library?

Maybe a better question is, how has Tk managed to keep beating up the
newer, more modern, more featureful, better documented toolkits
encroaching on his territory? What's Tk's secret weapon?