Unable to customize `alt-b` and `alt-f` for moving by words

Hi all,
I am use the mac version of TeXmacs, I want to realize emacs keybinding for moving forward and backward by words, using alt-b and alt-f. I expect the following code should work:

(delayed
 (lazy-keyboard-force)
(kbd-map
 (:mode in-text?)
 ("A-b" (begin (kbd-select traverse-left) (kbd-right) (kbd-left)))
 ("A-f" (begin (kbd-select traverse-right) (kbd-left) (kbd-right)))
 )

However, it does not; and it only gives b and f. (I have disabled mac’s default alt keybinding, thus it will not yield something like and ƒ).

Note if I use meta key (i.e., the Command key on mac) instead of alt key, it works.

(delayed
 (lazy-keyboard-force)
(kbd-map
 (:mode in-text?)
 ("M-b" (begin (kbd-select traverse-left) (kbd-right) (kbd-left)))
 ("M-f" (begin (kbd-select traverse-right) (kbd-left) (kbd-right)))
 )

Why I can not utilize alt key?

BTW, I can successfully implement alt-b and alt-f behavior on ubuntu; so this problem must be related to the macOS system.

Hi @vac, I think at the moment all TeXmacs Mac users are active only on the mailing list, perhaps you could post your question there.

Thank you for the reply. Yes, I think I should try the mailing list.
Later, if I get the solution, I will update it here.