Hiding mode-line in speedbar buffer

Question

I would like to hide the mode-line completely in a speedbar buffer. Calling (setq mode-line-format nil) in the buffer works temporarily, but I would like to make this setting permanent. Adding a hook using (add-hook 'speedbar-mode-hook (lambda () (setq mode-line-format nil))) has no effect. What is the correct way to achieve this?

I am using emacs 25.2.1 on macOS.

Answer 1

(require 'speedbar)

(defun speedbar-set-mode-line-format ()
  (setq mode-line-format nil))