Variable: kill-append-merge-undo
kill-append-merge-undo is a customizable variable defined in
simple.el.gz.
Value
nil
Documentation
Amalgamate appending kills with the last kill for undo.
When non-nil, appending or prepending text to the last kill makes
C-x u (undo) restore both pieces of text simultaneously.
This variable was added, or its default value changed, in Emacs 25.1.
Source Code
;; Defined in /usr/src/emacs/lisp/simple.el.gz
;; It has been argued that this should work like `self-insert-command'
;; which merges insertions in `buffer-undo-list' in groups of 20
;; (hard-coded in `undo-auto-amalgamate').
(defcustom kill-append-merge-undo nil
"Amalgamate appending kills with the last kill for undo.
When non-nil, appending or prepending text to the last kill makes
\\[undo] restore both pieces of text simultaneously."
:type 'boolean
:group 'killing
:version "25.1")