Add advice to mark-set command for multicursor selection

src/commands/mark.lisp

@@ -18,7 +18,7 @@
       (move-point (current-point) (pop-buffer-point))
       (progn
         (set-cursor-mark (current-point) (current-point))
-        (message "Mark set"))))
+        (when-real-cursor (message "Mark set")))))
 
 (define-command exchange-point-mark () ()
   "Exchange the current cursor position with the marked position."

src/cursors.lisp

@@ -123,3 +123,7 @@
                     (if not-lastp
                         (write-line string out)
                         (write-string string out))))))))
+
+(defmacro when-real-cursor (&body body)
+  `(unless (typep (current-point) 'fake-cursor)
+     ,@body))

src/internal-packages.lisp

@@ -621,7 +621,8 @@
    :make-fake-cursor
    :delete-fake-cursor
    :merge-cursor-killrings
-   :clear-cursors)
+   :clear-cursors
+   :when-real-cursor)
   ;; typeout.lisp
   (:export
    :*typeout-mode-keymap*