emacs-28 a905224: Improve documentation of 'shift-select-mode'

[Eli Zaretskii]

branch: emacs-28
commit a9052248da4296415260ea7710ab044e3f59ba77
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Improve documentation of 'shift-select-mode'
    
    * doc/emacs/mark.texi (Shift Selection): Document the 'permanent'
    value of 'shift-select-mode'.  Add index entry for that variable.
    (Bug#50954)
    
    * etc/NEWS: Update the entry for 'shift-select-mode'.
---
 doc/emacs/mark.texi | 7 ++++++-
 etc/NEWS            | 5 +++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/doc/emacs/mark.texi b/doc/emacs/mark.texi
index 20cb8ee..2461cb0 100644
--- a/doc/emacs/mark.texi
+++ b/doc/emacs/mark.texi
@@ -409,9 +409,14 @@ region by dragging the mouse, you can continue to extend 
the region
 using shifted cursor motion commands.  In either case, any unshifted
 cursor motion command deactivates the mark.
 
+@vindex shift-select-mode
   To turn off shift-selection, set @code{shift-select-mode} to
 @code{nil}.  Doing so does not disable setting the mark via mouse
-commands.
+commands.  If you set @code{shift-select-mode} to the value
+@code{permanent}, cursor motion keys that were not shift-translated
+will not deactivate the mark, so, for example, the region set by prior
+commands can be extended by shift-selection, and unshifted cursor
+motion keys will extend the region set by shift-selection.
 
 @node Disabled Transient Mark
 @section Disabling Transient Mark Mode
diff --git a/etc/NEWS b/etc/NEWS
index f8c045f..cff306e 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -989,11 +989,12 @@ further tweak whether to complete or indent.
 ---
 ** 'indent-tabs-mode' is now a global minor mode instead of just a variable.
 
----
++++
 ** New choice 'permanent' for 'shift-select-mode'.
 When the mark was activated by shifted motion keys, non-shifted motion
 keys don't deactivate the mark after customizing 'shift-select-mode'
-to 'permanent'.
+to 'permanent'.  Similarly, the active mark will not be deactivated by
+typing shifted motion keys.
 
 +++
 ** The "Edit => Clear" menu item now obeys a rectangular region.