Tk.Menu `underline` does not consider `activeborderwidth`

[rtommy]

Bug report

Bug description:

This issue is related to underline attribute of a menu item command.

When the Menu has activeborderwidth bigger than 1 and the menu item has underline, the position of the actual text (character) underline does not consider activeborderwidth and the _ is not under the character where it should be (text shifted by activeborderwidth). Screenshot is below.

It seems to be an issue with Tcl/Tk itself therefore, I raised a ticket there: 844c0be72d433c24441926eb8a84bda1e9cbee72

Example python code: compare menu items under ActiveBW1 and ActiveBW4.

from tkinter import *

root = Tk()
menu = Menu(root)

abw1 = Menu(menu, tearoff=0, activeborderwidth=1, borderwidth=1)
menu.add_cascade(menu=abw1, label='ActiveBW1', underline=0)
abw1.add_command(label='Menu Item 1', underline=0, accelerator='Ctrl-1')
abw1.add_command(label='Menu Item 2', underline=0, accelerator='Ctrl-2')

abw4 = Menu(menu, tearoff=0, activeborderwidth=4, borderwidth=4)
menu.add_cascade(menu=abw4, label='ActiveBW4', underline=0)
abw4.add_command(label='Menu Item 3', underline=0, accelerator='Ctrl-3')
abw4.add_command(label='Menu Item 4', underline=0, accelerator='Ctrl-4')

root.config(menu=menu)
root.mainloop()

(The example above is not the best since the Menu names have the same first letter, and the item names too)

However, I believe there could be a workaround to actually achieve the same behaviour without using underline.
I don't need the actual character underline, but I would need the keyboard shortcut.

How can I add keyboard shortcut bindings for the logic of: select Menu and the item?

In the following example I can select menu items by keyboard shorcuts:

• Alt-o then o results showinfo "1"
• Alt-o then t results showinfo "2"
• Alt-t then t results showinfo "3"
• Alt-t then f results showinfo "4"

Note, accelerators are not really considered.

root = Tk()
menu = Menu(root)

abw1 = Menu(menu, tearoff=0, activeborderwidth=1, borderwidth=1)
menu.add_cascade(menu=abw1, label='One', underline=0)
abw1.add_command(label='one', underline=0, accelerator='Ctrl-1', command=lambda: showinfo("1","1"))
abw1.add_command(label='two', underline=0, accelerator='Ctrl-2', command=lambda: showinfo("2","2"))

abw4 = Menu(menu, tearoff=0, activeborderwidth=4, borderwidth=4)
menu.add_cascade(menu=abw4, label='Two', underline=0)
abw4.add_command(label='three', underline=0, accelerator='Ctrl-3', command=lambda: showinfo("3","3"))
abw4.add_command(label='four',  underline=0, accelerator='Ctrl-4', command=lambda: showinfo("4","4"))

root.config(menu=menu)
root.mainloop()

I would need the same result by adding bindings and without using underline (since it has the original fault mention at the beginning).
I want to 'open' the Menu first and then select an item, all with shortcuts.

CPython versions tested on:

3.12

Operating systems tested on:

Windows

[rtommy]

The Tcl/Tk issue has been fixed in 088283d026.
I'm not sure whick version (9.x.x or 8.x.x) will have it and it seems backporting is not done.
So I'm not sure how to eventually deliver it in python.

Additionally, ...

I had some further testings and dig in. The underline is an OS specific thing, it means it adds an ampersand in front of the character based on the underline parameter (number) and the OS knows to underline it (or not) based on the OS settings.

In Windows 11 (and similarly in older versions) under Accessibility > Keyboard the Underline access keys setting will determine what to do.

This means .bind() is not used in this situation. So if I want to use keyboard shortcuts to select a tk.Menu (open/close; display/undisplay) and the select a menu item in it, I need to use underline.

Now, the question is could I "hide" the underline? Technically, it should be possible via SystemParametersInfo but it does not seem to fully work for me.

import ctypes

SPI_GETKEYBOARDCUES = 4106  # 0x100A
SPI_SETKEYBOARDCUES = 4107  # 0x100B
 
user32 = ctypes.WinDLL('user32', use_last_error=True)

def get_menu_underlines():
    showMenuAccelerators = ctypes.c_bool(False)
    res = user32.SystemParametersInfoW(SPI_GETKEYBOARDCUES, 0, ctypes.byref(showMenuAccelerators), 0)
    if not res: print("GET:", ctypes.WinError(ctypes.GetLastError()))
    else: print("Result:", showMenuAccelerators.value)

def set_menu_underlines(val=False):
    res = user32.SystemParametersInfoW(SPI_SETKEYBOARDCUES, 0, val, 0)
    if not res: print("SET:", ctypes.WinError(ctypes.GetLastError()))

1. "Underline access keys" is OFF

   When the OS setting is OFF, I am able to turn it ON, this works.

   get_menu_underlines()   
   set_menu_underlines(True)
   get_menu_underlines()

   Result:

   Result: False
   Result: True
   

2. "Underline access keys" is ON

   BUT when the OS setting is ON, I am NOT able to turn it OFF hence, this does not work.
   And this is what I would need actually....

   get_menu_underlines()   
   set_menu_underlines(False)
   get_menu_underlines()

   Result:

   Result: True
   Result: True
   

Can anyone have a look, test and let me know why it does not work as expected?

It seems I can't overwrite the setting if it is ON?

[rtommy]

The fix has been backported to both 8.7 and 8.6. Is this going to be delivered in python?

[terryjreedy]

We will eventually upgrade to either the next 8.6 (8.6.16) or 9.0. I hope the latter.