Add new value `dont-save' to `deactivate-mark'

* etc/NEWS: Announce new value of `deactivate-mark'.

* lisp/simple.el (deactivate-mark): Handle new value.
(bug#57147)

* src/keyboard.c (syms_of_keyboard): Update doc string of
`deactivate-mark'.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 719226caedc..05c68ea7fbc 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -12650,10 +12650,14 @@ cancels any modification.  */);
 
   DEFSYM (Qdeactivate_mark, "deactivate-mark");
   DEFVAR_LISP ("deactivate-mark", Vdeactivate_mark,
-	       doc: /* If an editing command sets this to t, deactivate the mark afterward.
+    doc: /* If an editing command sets this to t, deactivate the mark afterward.
 The command loop sets this to nil before each command,
 and tests the value when the command returns.
-Buffer modification stores t in this variable.  */);
+Buffer modification stores t in this variable.
+
+By default, deactivating the mark will save the contents of the region
+according to `select-active-regions'.  If this is set to the symbol
+`dont-save', the region will not be saved.*/);
   Vdeactivate_mark = Qnil;
   Fmake_variable_buffer_local (Qdeactivate_mark);