This section describes the predefined mega-widget classes that are present in the Tix extension. For options that are equivalent to the standard Tk widget options, only the names are listed. Refer to the "Standard Widget Options" section of Chapter 3, Tk Core Commands, for the full definition of these options. Since almost all mega-widget classes are derived from another mega-widget class, it is important to refer to the description of the superclass to see the full API of a mega-widget class. Inherited commands, options, and subwidgets are sometimes listed for a megawidget class when they are overridden or are an integral part of the mega-widget’s function.