Variable: rectangle-indicate-zero-width-rectangle
rectangle-indicate-zero-width-rectangle is a customizable variable
defined in rect.el.gz.
Value
t
Documentation
If non-nil, make zero-width rectangles visible on display.
This variable was added, or its default value changed, in Emacs 31.1.
Probably introduced at or before Emacs version 31.1.
Source Code
;; Defined in /usr/src/emacs/lisp/rect.el.gz
(defcustom rectangle-indicate-zero-width-rectangle t
"If non-nil, make zero-width rectangles visible on display."
:version "31.1"
:type 'boolean)