Issue a message on `C-x o' and there's no other window

* lisp/window.el (other-window): Issue a message when the user
types `C-x o' and there's no other window to select (bug#10999).

1 files changed, 5 insertions, 0 deletions

diff --git a/lisp/window.el b/lisp/window.el
index 2345f398e72..723671efa57 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -3926,6 +3926,7 @@ select.  The argument ALL-FRAMES has the same meaning as in
 always effectively nil."
   (interactive "p")
   (let* ((window (selected-window))
+         (original-window window)
          (function (and (not ignore-window-parameters)
                         (window-parameter window 'other-window)))
          old-window old-count)
@@ -3968,6 +3969,10 @@ always effectively nil."
            (t
             (setq count (1+ count)))))
 
+        (when (and (eq window original-window)
+                   (called-interactively-p 'interactive))
+          (message "No other window to select"))
+
         (select-window window)
         ;; Always return nil.
         nil))))