Purpose: describe what the term ''widget'' means

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A ''widget'' is a term used in graphical user interface (GUI)
circles in connection to some component of a GUI application.  
While most widgets have the potential of visual representation,
this need not be the case - for instance, container widgets
like frames don't actually show up on the screen.

See [Tk syntax help] for a list of Tk specific commands, most of which
are widgets: [button] - [canvas] - [checkbutton] - [entry] - [label] - [menu] - [message] - [radiobutton] - [scrollbar] - [text] etc.
Note that in Tk, one has several ways one can control visual aspects of widgets:

   * externally, via the X resource database
   * at creation time, on the ''command line''
   * later, using the ''-config'' option
   * via the [option] database
   * in some cases, via special objects, like [font]

[[are there other ways of influencing these?]]






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Some systems call these "controls."  I've also heard "gadgets."  -- CLN

'''EE''': From
'''The X Window System: Programming And Applications With Xt, OSF/Motif Edition''' by Douglas A. Young. (First edition, sixth printing, published in 1990):

 In addition to widgets, Motif provides a user interface component known
 as a gadget. Gadgets are identical to widgets, except that they have no
 window of their own. A gadget must display text or graphics in the
 window provided by its parent, and must also rely on its parent for
 input. [[...]] From the application programmer's viewpoint, gadgets can
 be used exactly the same way as other display widgets, except for the
 following restrictions. Gadgets cannot support event handlers,
 translations, or popup children. Gadgets can support callback functions
 and have the same appearance as the corresponding widgets.

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[Category GUI]