Welch essential for learning Tkinter well?

[Dick Moores]

In a couple of places recently I've seen Brent Welch's _Practical 
Programming in Tcl & Tk_ (<http://tinyurl.com/ynlk8b>) recommended 
for learning Tkinter well.

So a couple of questions:

1) Is it really good for learning Tkinter, even though it doesn't 
mention Tkinter at all (in the 4th edition at least)?

2) If it is good for learning Tkinter, can I get by with a cheaper, 
used copy of the 3rd edition?

Thanks,

Dick Moores