New Rmail option 'rmail-show-message-set-modified'

* lisp/mail/rmail.el (rmail-show-message-set-modified): New
option.
(rmail-show-message-1): If 'rmail-show-message-set-modified' is
non-nil, don't reset the buffer's modified state.  (Bug#45941)

* etc/NEWS: Announce the new option.

1 files changed, 5 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index a6fd51b8a2a..11fca4fecb6 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1138,6 +1138,11 @@ bindings, will be aborted, and Emacs will not ask you whether to
 enlarge 'max-specpdl-size' to complete the rendering.  The default is
 t, which preserves the original behavior.
 
+---
+*** New user option 'rmail-show-message-set-modified'.
+If set non-nil, showing an unseen message will set the Rmail buffer's
+modified flag.
+
 ** Apropos
 
 *** New commands 'apropos-next-symbol' and 'apropos-previous-symbol'.