Purpose: describe what a widget is
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.
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 y 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.