Online python Tkinter documentation (https://docs.python.org/3/library/tkinter.html) lacks many features. The main part I find lacking is documentation on methods, as many of them either aren't listed in the documentation and/or take *args as the only parameter, rather than defined parameters. 

Not sure how in-depth docs from effbot were, but those are not currently available.

Existing documentation in the source code (https://github.com/python/cpython/blob/3.9/Lib/tkinter/__init__.py) seems to be a good start to adding to the online documentation.