Allow control of indicating empty rectangular selections

* lisp/rect.el (rectangle-indicate-zero-width-rectangle): New user
option.
(rectangle--highlight-for-redisplay): Use it to decide whether to
indicate empty rectangles on display.  (Bug#16403)

* etc/NEWS: Announce the feature.

(cherry picked from commit cecaec20e7ad525719d7d05233f1e6e2ba6a1475)

diff --git a/lisp/rect.el b/lisp/rect.el
index 4aa5a8ad4d167b1f71ea90ec01897dfcd3c307cd..1211b3ccd56472154fcb078d1f297b68777fe29b 100644 (file)
--- a/lisp/rect.el
+++ b/lisp/rect.el
@@ -446,6 +446,11 @@ With a prefix (or a FILL) argument, also fill too short lines."
   :version "25.1"
   :type 'boolean)
 
+(defcustom rectangle-indicate-zero-width-rectangle t
+  "If non-nil, make zero-width rectangles visible on display."
+  :version "31.1"
+  :type 'boolean)
+
 (defun rectangle--string-preview ()
   (when rectangle-preview
     (let ((str (minibuffer-contents)))
@@ -946,7 +951,8 @@ Ignores `line-move-visual'."
                         (overlay-put ol 'after-string str))))
                    ((overlay-get ol 'after-string)
                     (overlay-put ol 'after-string nil)))
-                  (when (and (= leftcol rightcol) (display-graphic-p))
+                  (when (and (= leftcol rightcol) (display-graphic-p)
+                             rectangle-indicate-zero-width-rectangle)
                     ;; Make zero-width rectangles visible!
                     (overlay-put ol 'after-string
                                  (concat (propertize