I found I always accidentally confused [C-x 5 0] and [C-x 5 o] keybindings. I hope Emacs can add add
prompt confirmation to avoid user accidentally delete frame. Because it can't undo with winner
package etc.

#+begin_src emacs-lisp
(defun my/delete-frame-confirm (origin-func &optional args)
  "Ask user to confirm whether really delete frame.
To avoid accidentally [C-x 5 0] delete frame which confused with keybinding [C-x 5 o]."
  (if (yes-or-no-p "Are you sure to delete current frame? ")
      (apply origin-func args)
    (message "I don't want to delete frame accidently!")))

(advice-add 'delete-frame :around #'my/delete-frame-confirm)
#+end_src

What do you think?

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