I have used Grayson's book - purchased and read many years ago now though. I am only an occasional GUI programmer, but have recently moved away from Tkinter and ttk towards wxPython - mainly because I am very dissatisfied with the lack of widgets to choose from. (new from 2.7 on) ttk supposedly added to the basic TkInter kit but is extremely difficult to work out due to lack of documentation i.e. I quickly wanted to use styles and finding some easy documentation that explained how all that worked was impossible - despite searching the Internet for hours (perhaps I was just unlucky? :-)).
For learning wxPython I am using "wxPython in Action" by Noel Rappin and Robin Dunn. Neither book is about learning Python though - they are both aimed at users who have at least a basic Python background and want to learn about the particular GUI toolkit in question. Even though I am on my first wxPython GUI, I am extremely happy that I made the switch - I am already using basic wxPython widgets that were just not available under TkInter/ttk, creating a much more intuitive interface (IMO :-)) for my users. Best of luck in your choices, Peter -- http://mail.python.org/mailman/listinfo/python-list
