tk.rst tells, among other things:

"`Tkinter`'s chief virtues are that it is fast, and that it usually comes
bundled with Python. Although it has been used to create some very good
applications,  including IDLE, it has weak documentation ..."

Why does it say Tkinter has weak documentation ? There is a printed book
("Python and Tkinter Programming"), several online tutorials and
references, there is a wiki too, the mail list and possibly something
else I've missed.