From: Dmitry Gutov<dgutov@yandex.ru>
Date: Thu, 30 Sep 2021 14:04:28 +0300
On 30.09.2021 07:59, Lars Ingebrigtsen wrote:
-(define-key global-map (kbd "C-?") 'undo-redo)
+(define-key global-map "\C-?" 'undo-redo)
Sorry about the breakage.
But "\C-?" and (kbd "C-?") are not the same: the former evaluates to a
string containing the DEL char.
The latter returns something like [67108927], and that's how we avoided
trying to bind 'undo-redo' to Backspace. This binding only works in GUI
Emacs, of course.