This is a menu that provides all the same features as the toolbars, with a few more features; some stuff from IE, Define Subset & in the Help menu are MSDN Library Help & MSDN Online, which jump to a topic in the MSDN and to http://www.microsoft.com/msdn/ respectively. The other menu items are all accessible from other parts of the UI such as the toolbar & context menus and so the only reason for an author to include the menu would be to let the user access the Define Subset command, which can be useful for documentation containing information on a diverse range of topics, especially for the index & search tabs. The two MSDN menu items (that do nothing outside the MSDN) could confuse the user, however. It is probable that MS would have fixed this feature for Help 2.