image-dired: Remove spurious message on C-<mouse-1>

* lisp/image/image-dired.el (image-dired-thumbnail-mode-map): Fix
spurious message about C-<down-mouse-1> being undefined.

diff --git a/lisp/image/image-dired.el b/lisp/image/image-dired.el
index 6b6399f7f4da4290e2458b6b40140e29969c2041..478de4e0ee4dddbb1f657d45f4365c29e580ce50 100644 (file)
--- a/lisp/image/image-dired.el
+++ b/lisp/image/image-dired.el
@@ -882,12 +882,7 @@ You probably want to use this together with
   "<down-mouse-1>"   #'image-dired-mouse-select-thumbnail
   "<down-mouse-2>"   #'image-dired-mouse-select-thumbnail
   "<down-mouse-3>"   #'image-dired-mouse-select-thumbnail
-  ;; Seems I must first set C-down-mouse-1 to undefined, or else it
-  ;; will trigger the buffer menu.  If I try to instead bind
-  ;; C-down-mouse-1 to `image-dired-mouse-toggle-mark', I get a message
-  ;; about C-mouse-1 not being defined afterwards.  Annoying, but I
-  ;; probably do not completely understand mouse events.
-  "C-<down-mouse-1>" #'undefined
+  "C-<down-mouse-1>" #'ignore           ; Don't open the buffer menu.
   "C-<mouse-1>"      #'image-dired-mouse-toggle-mark)
 
 (easy-menu-define image-dired-thumbnail-mode-menu image-dired-thumbnail-mode-map