Variable: message-expand-name-standard-ui
message-expand-name-standard-ui is a customizable variable defined in
message.el.gz.
Value
nil
Documentation
If non-nil, use the standard completion UI in message-expand-name.
E.g. this means it will obey completion-styles and other such settings.
This variable was added, or its default value changed, in Emacs 27.1.
Probably introduced at or before Emacs version 27.1.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/message.el.gz
(defcustom message-expand-name-standard-ui nil
"If non-nil, use the standard completion UI in `message-expand-name'.
E.g. this means it will obey `completion-styles' and other such settings."
:version "27.1"
:type 'boolean)