Widgets
The widget is the basic building block of most X applications. A widget
can be considered an object in the object oriented paradigm. A widget has
certain properties, and it can have certain methods applied to it.
Some of the common properties associated with a widget are a window,
a geometry, colors (forgound and background) and a position in the widget
hierarchy. Not all widgets have all of these properties, but most of them
do. The value of these properties are specified by the application resources
(explained later).
Some of the common methods that can be applied to a widget are realize
(create), resize, and repaint. Other methods may be available depending
on the nature of the widget.
An application is built by combining widgets into a useful user interface.
This combination is called the widget hierarchy and can be though of as
a tree structure. Each application will have a widget tree that is specific
(and probably unique) to that application.
Identifying the widgets
Each type of widget is identified by a class. The class name of the widget
usually described the function of the widget, such as Label, ComandButton,
and ScrollBar. An application may have multiple instances of the same widget
class.
In an application, each instance of a widget is identified by a unique
name. The name should describe how the widget is being used, such as quitButton,
helpButton, and fileMenu.
Viewing the widgets
Some programs are provided for working with the Athena Widgets. These programs
show you the widget hierarchy in a couple of different formats, and allow
you
to interactively manipulate them.
listres
This utility simply prints out each widget in
the Athena widget set, and shows its ancestry.
viewres
This utility shows the widget ancestory graphically.
It uses the Tree widget to display this information.
editres
Editres is an interactive tool that can be used
to dynamically modify the properties of an Athena widget. Only applications
built using the Athena widgets can utilize utility.
Editres can be used to identify a widget in the widget tree, and modify
some properties of that widget.
