Subject: bug#30452: [PATCH] Use 'make-sparse-keymap' rather than 'copy-keymap'

From: Stefan Monnier <[email-masked]>
Date: Sat, 19 Jan 2019 10:33:12 -0500

>>  (defvar tabulated-list-mode-map
>> -  (let ((map (copy-keymap special-mode-map)))
>> +  (let ((map (make-sparse-keymap)))
>>      (set-keymap-parent map button-buffer-map)

Nowadays we can inherit from both with something like

    (set-keymap-parent map (make-composed-keymap
                            button-buffer-map
                            special-mode-map))

-- Stefan