[PATCH] Re: Proposal to change cursor appearance to indicate region activation

[Kelly Dean]

Stefan Monnier wrote on 23 Nov 2013:
>> (add-hook 'deactivate-mark-hook (lambda () (setq cursor-type t)))
>> (add-hook 'activate-mark-hook (lambda () (setq cursor-type 'bar)))
>
> I like the idea, but this collides with other uses of cursor-type.
> Could someone cook up a patch which only does the above if cursor-type
> has not been modified (and which lets users opt-out if they prefer).
> Also, the patch should directly modify deactivate-mark and activate-mark
> rather than using the hooks.

Ok. Patch attached below.

With dynamic-cursor-mode turned off, it won't interfere with other uses of 
cursor-type.

And if you enable/disable dynamic-cursor-mode buffer-locally, it won't 
interfere with other uses of cursor-type in other buffers. In fact I have a 
couple of minor modes in my own packages that rely on this separation.

Third hunk adjusted to avoid conflict with current Emacs trunk.
--- emacs-24.4/lisp/simple.el
+++ emacs-24.4/lisp/simple.el
@@ -4391,6 +4391,12 @@
 (declare-function x-selection-exists-p "xselect.c"
                   (&optional selection terminal))
 
+(defcustom dynamic-cursor-mode 't
+  "If non-nil, `cursor-type' is set dynamically to reflect `mark-active'."
+  :type 'boolean
+  :version "25.1"
+  :group 'editing-basics)
+
 (defun deactivate-mark (&optional force)
   "Deactivate the mark.
 If Transient Mark mode is disabled, this function normally does
@@ -4430,6 +4436,7 @@
      ((eq transient-mark-mode 'lambda)
       (setq transient-mark-mode nil)))
     (setq mark-active nil)
+    (if dynamic-cursor-mode (setq cursor-type 't))
     (run-hooks 'deactivate-mark-hook)
     (redisplay--update-region-highlight (selected-window))))
 
@@ -4445,3 +4452,4 @@
+      (if dynamic-cursor-mode (setq cursor-type 'bar))
       (run-hooks 'activate-mark-hook))))
 
 (defun set-mark (pos)