1 files changed, 3 insertions, 0 deletions

diff --git a/lisp/window.el b/lisp/window.el
index 2b5a4ab161d..188b3acf311 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -36,6 +36,9 @@ of this construct.
 However, if a window has become dead, don't get an error,
 just refrain from reselecting it."
   `(let ((save-selected-window-window (selected-window))
+         ;; It is necessary to save all of these, because calling
+         ;; select-window changes frame-selected-window for whatever
+         ;; frame that window is in.
          (save-selected-window-alist
           (mapcar (lambda (frame) (list frame (frame-selected-window frame)))
                   (frame-list))))