The transition from Tkinter/tkinter to tkinter/_tkinker in 3.x docs is
incomplete.

1. There are several places not in titles or beginning of sentences
where Tkinter (roman type) needs to be replaced with tkinter (fixed
type, as elsewhere).

2. "24.1.1. Tkinter Modules
Most of the time, the tkinter is all" <<delete 'the' before tkinter>>

24.1.6.4. Coupling Widget Variables
 "from a class called Variable, defined in the tkinter." ditto

3. 24.1.5. How Tk and Tkinter are Related
"tkinter (C) 
These commands and their arguments will be passed to a C function in the
tkinter - note the lowercase - extension module"
Change 'tkinter' to '_tkinter' and 'lowercase' to 'underscore'.

"Xlib (C) 
the Xlib library to draw graphics on the screen. "

Is this still true? Or does Tk now use native libraries?

Not 3.x specific.

10. "Specifically, the man pages in the mann directory are most useful."
Is 'mann' literally correct? a typo? or meant to mean 'man#', where # is
a digit? If the last, either man# or mann with the last 'n' a different
font would be clearer to me.

This is, of course, *nix specific.

11. "Credits:
Tkinter was written by Steen Lumholt and Guido van Rossum. 
Tk was written by John Ousterhout while at Berkeley. "
Except for the first two lines, the entries are in historical order, so
I would reverse the first two.
 
12. 24.1.6.6. Tk Option Data Types
"To specify an X bitmap filename, give the full path to the file,
preceded with an @, as in "@/usr/contrib/bitmap/gumby.bit"."
*nix only? what about windows .bmp file?

13. (ttk section) 24.2.3.1. Standard Options
"0, 1 or an empty is return." => "0, 1 or an empty string is returned."


PS. I like the colors of the option-description tables.