diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 448e319cfc4..355fae2103a 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2006-05-02  Chong Yidong  <cyd@mit.edu>
+
+	* msb.el (msb): If EVENT is a down event, read and discard the up
+	event.
+
 2006-05-02  Reiner Steib  <Reiner.Steib@gmx.de>
 
 	* startup.el (command-line-1): Refer to Lisp manual when
diff --git a/lisp/msb.el b/lisp/msb.el
index 95cbfc85df4..61ddce5dae0 100644
--- a/lisp/msb.el
+++ b/lisp/msb.el
@@ -473,6 +473,11 @@ selects that window.
 See the function `mouse-select-buffer' and the variable
 `msb-menu-cond' for more information about how the menus are split."
   (interactive "e")
+  ;; If EVENT is a down-event, read and discard the
+  ;; corresponding up-event.
+  (and (eventp event)
+       (memq 'down (event-modifiers event))
+       (read-event))
   (let ((old-window (selected-window))
 	(window (posn-window (event-start event))))
     (unless (framep window) (select-window window))