RE: Colors and other questions

I have the answers to some of my questions, but it just brings up more
questions.

If I change every instance of "ttk__" in my sample code, except for the
combobox (otherwise there was an error), the colors work much better.
For (1), I'm able to change the background color in an entry widget.
For (5), I can change the colors of a button, and for (6), I can change
the colors of a radio button.

So, what is the difference between widgets that have "ttk__" in their
name and those that don't?  If I want to find help on these widgets,
where do I look?  Why is there a difference and what are the advantages
and disadvantages to one over the other?  If tkx is supposed to be a
thin wrapper over Tcl/Tk, does that mean there are different types of
entry/button/radio widgets in Tcl/Tk?  Any answers to the other
questions from the previous post (#2, 3, 4, 7, 8, 9, 10)?

Thanks,
David