Improve behavior of `lost-selection-mode' with multiple buffers

* etc/NEWS: Announce new hook `post-select-region-hook'.

* lisp/select.el (lost-selection-last-region-buffer): New
variable.
(lost-selection-post-select-region-function): New function.
Deactivate the mark if the buffer changed.
(lost-selection-mode): Add new hook.

* src/keyboard.c (command_loop_1): Run that hook when
appropriate.
(syms_of_keyboard): New hook `post-select-region-hook'.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 7c13ac96114..1d505c13be3 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -1590,9 +1590,12 @@ command_loop_1 (void)
                 {
                   Lisp_Object txt
                     = call1 (Vregion_extract_function, Qnil);
+
                   if (XFIXNUM (Flength (txt)) > 0)
                     /* Don't set empty selections.  */
                     call2 (Qgui_set_selection, QPRIMARY, txt);
+
+                  CALLN (Frun_hook_with_args, Qpost_select_region_hook, txt);
                 }
 
               if (current_buffer != prev_buffer || MODIFF != prev_modiff)
@@ -12080,6 +12083,9 @@ syms_of_keyboard (void)
   DEFSYM (Qpre_command_hook, "pre-command-hook");
   DEFSYM (Qpost_command_hook, "post-command-hook");
 
+  /* Hook run after the region is selected.  */
+  DEFSYM (Qpost_select_region_hook, "post-select-region-hook");
+
   DEFSYM (Qundo_auto__add_boundary, "undo-auto--add-boundary");
   DEFSYM (Qundo_auto__undoably_changed_buffers,
           "undo-auto--undoably-changed-buffers");
@@ -13028,6 +13034,12 @@ not recorded.  The non-nil value countermands `inhibit--record-char',
 which see.  */);
   record_all_keys = false;
 
+  DEFVAR_LISP ("post-select-region-hook", Vpost_select_region_hook,
+    doc: /* Abnormal hook run after the region is selected.
+This usually happens as a result of `select-active-regions'.  The hook
+is called with one argument, the string that was selected.  */);;
+  Vpost_select_region_hook = Qnil;
+
   pdumper_do_now_and_after_load (syms_of_keyboard_for_pdumper);
 }