Update comments to reflect changes in xmenu.c.

src/termhooks.h

@@ -249,7 +249,7 @@ enum event_kind
   buffer_switch_event,		/* A process filter has switched buffers.  */
   delete_window_event,		/* An X client said "delete this window".  */
   menu_bar_event,		/* An event generated by the menu bar.
-				   The frame_or_window field holds the
+				   The frame_or_window field's cdr holds the
 				   Lisp-level event value.
 				   (Only the toolkit version uses these.)  */
   iconify_event,		/* An X client iconified this window.  */
@@ -278,8 +278,8 @@ struct input_event {
 
   /* This field is copied into a vector while the event is in the queue,
      so that garbage collections won't kill it.  */
-  /* In a menu_bar_event, this holds the Lisp object
-     that is the event's value.  */
+  /* In a menu_bar_event, this is a cons cell whose car is the frame
+     and whose cdr is the Lisp object that is the event's value.  */
   Lisp_Object frame_or_window;
 
   int modifiers;		/* See enum below for interpretation.  */