MenuItem -- Overview
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 Class Function

 MenuItem()      Create a new MenuItem object
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 Exported Instance Variables

 caption         Describes menu option or menu separator
 cargo           User-definable variable
 checked         Logical value which indicates a check mark
 data            Contains code block or a PopUpMenu object
 enabled         Logical value indicating if menu item is selected
 id              Numeric value which identifies the menu item
 message         String that describes the menu item
 shortcut        Numeric value indicating the key to activate menu selection
 style           String indicating the characters used by PopUpMenu:display()
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 Exported Methods

 isPopUp()       Indicates whether MenuItem:data contains a PopUpMenu object