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usual(n)                                          [incr Tk]                                         usual(n)



NAME
       usual - access default option-handling commands
            for a mega-widget component

SYNOPSIS
       usual ?tag? ?commands?


DESCRIPTION
       The  usual  command  is  used  outside  of  an [incr Tcl] class definition to define the usual set of
       option-handling commands for a component widget.  Option-handling commands are used when a  component
       is registered with the Archetype base class via the "itk_component add" method.  They specify how the
       component's configuration options should be integrated into the composite option list for  the  mega-widget. megawidget.
       widget.  Options can be kept, renamed, or ignored, as described in the Archetype man page.

       It  is  tedious  to include the same declarations again and again whenever components are added.  The
       usual command allows a standard code fragment to be registered for each widget class, which  is  used
       by  default to handle the options.  All of the standard Tk widgets have usual declarations defined in
       the [incr Tk] library.  Similar usual declarations should be created whenever a new mega-widget class
       is conceived.  Only the most-generic options should be included in the usual declaration.

       The  tag name is usually the name of a widget class, which starts with a capital letter; however, any
       string registered here can be used later with the usual command described on the Archetype man  page.

       If  the  commands  argument  is  specified, it is associated with the tag string, and can be accessed
       later via itk_component add.

       If only the tag argument is specified, this command looks for an existing tag name  and  returns  the
       commands  associated with it.  If there are no commands associated with tag, this command returns the
       null string.

       If no arguments are specified, this command returns a list of all tag names previously registered.


EXAMPLE
       Following is the usual declaration for the standard Tk button widget: usual Button {
           keep -background -cursor -foreground -font
           keep -activebackground -activeforeground -disabledforeground
           keep -highlightcolor -highlightthickness
           rename -highlightbackground -background background Background } Only the options  that  would  be
       common  to  all buttons in a single mega-widget are kept or renamed.  Options like "-text" that would
       be unique to a particular button are ignored.


KEYWORDS
       itk, Archetype, component, mega-widget



itk                                                  3.0                                            usual(n)