Comment changes.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/xmenu.c b/src/xmenu.c
index 6de1dcb2bd1..bb8cb19cbdf 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -2180,21 +2180,27 @@ set_frame_menubar (f, first_time, deep_p)
       /* If there has been no change in the Lisp-level contents
          of the menu bar, skip redisplaying it.  Just exit.  */
 
+      /* Compare the new menu items with the ones computed last time.  */
       for (i = 0; i < previous_menu_items_used; i++)
         if (menu_items_used == i
             || (!EQ (previous_items[i], XVECTOR (menu_items)->contents[i])))
           break;
       if (i == menu_items_used && i == previous_menu_items_used && i != 0)
         {
+          /* The menu items have not changed.  Don't bother updating
+             the menus in any form, since it would be a no-op.  */
           free_menubar_widget_value_tree (first_wv);
           discard_menu_items ();
           unbind_to (specpdl_count, Qnil);
           return;
         }
 
+      /* The menu items are different, so store them in the frame.  */
       f->menu_bar_vector = menu_items;
       f->menu_bar_items_used = menu_items_used;
 
+      /* This calls restore_menu_items to restore menu_items, etc.,
+         as they were outside.  */
       unbind_to (specpdl_count, Qnil);
 
       /* Now GC cannot happen during the lifetime of the widget_value,