The SCA/DECwindows interface provides pull-down menus, pop-up menus,
  and dialog boxes that allow you to enter and/or get additional information
  about menu items.

  To display the contents of a pull-down menu, position the pointer on an
  item in the menu bar and click on MB1.  For example, if you choose File
  in the menu bar, the File menu name is highlighted and a pull-down menu
  appears.  To choose a menu item, move the pointer down to
  the desired item and click on MB1.

  To display the contents of a pop-up menu, position the pointer within a
  window and click on MB3.  To choose menu items,  position the pointer on
  the desired item then click on MB3 again.  To avoid choosing an item on a
  pop-up menu, click MB3 outside of the menu borders.

  To get context-sensitive help on pull-down and pop-up menu items, do the
  following:

    o  Position the pointer on the item for which you want help
    o  Press and hold MB1.
    o  Press the Help key on the keyboard
    o  Release MB1.

  The help text appears in a separate help window. Additional requests
  for context-sensitive help change the topic in the help window.