Tk 8.7: TIP 577 breaks tkinter.Menu.index()

[chrstphrchvz]

Bug report

One effect of TIP 577 is that as of Tk 8.7, the index command for menus will now return an empty string instead of none, leading to an error in tkinter.Menu.index():

>>> m.index('none')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/user/git/cpython/Lib/tkinter/__init__.py", line 3434, in index
    return self.tk.getint(i)
           ^^^^^^^^^^^^^^^^^
_tkinter.TclError: expected integer but got ""

It should be easy to accommodate both the new and old behavior.

Linked PRs

• gh-103685: Fix tkinter.Menu.index() for Tk 8.7 #103686
• [3.11] gh-103685: Fix tkinter.Menu.index() for Tk 8.7 (GH-103686) #103734

[terryjreedy]

Thanks for making a start on preparing for 8.7+ & 9.0+