726 lines
20 KiB
XML
726 lines
20 KiB
XML
<chapter id='Athena_Widgets_and_The_Intrinsics'>
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<title>Athena Widgets and The Intrinsics</title>
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<para>
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The X Toolkit is made up of two distinct pieces, the Xt Intrinsics and a
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widget set. The Athena widget set is a sample implementation of a
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widget set built upon the Intrinsics. In the X Toolkit, a widget is the
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combination of an X window or subwindow and its associated input and
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output semantics.
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</para>
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<para>
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Because the Intrinsics provide the same basic functionality to all widget
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sets it may be possible to use widgets from the Athena widget set with
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other widget sets based upon the Intrinsics. Since widget sets may also
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implement private protocols, all functionality may not be available when
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mixing and matching widget sets. For information about the Intrinsics, see
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the <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>.
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</para>
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<para>
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The Athena widget set is a library package layered on top of the Intrinsics
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and Xlib that provides a set of user interface tools sufficient to build
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a wide variety of applications. This layer extends the basic
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abstractions provided by X and provides the next layer of functionality
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primarily by supplying a cohesive set of sample widgets. Although the
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Intrinsics are a Consortium standard, there is no standard widget set.
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</para>
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<para>
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To the extent possible, the Intrinsics are "policy-free". The application
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environment and widget set, not the Intrinsics, define, implement, and
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enforce:
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</para>
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<itemizedlist>
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<listitem><para>Policy</para></listitem>
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<listitem><para>Consistency</para></listitem>
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<listitem><para>Style</para></listitem>
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</itemizedlist>
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<para>
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Each individual widget implementation defines its own policy. The X Toolkit
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design allows for, but does not necessarily encourage, the free mixing
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of radically differing widget implementations.
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</para>
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<sect1 id='Introduction_to_the_X_Toolkit'>
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<title>Introduction to the X Toolkit</title>
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<para>
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<!-- .LP -->
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<!-- .XS -->
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<!-- Introduction to the X Toolkit -->
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<!-- .XE -->
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<!-- .IN "introduction" "" "@DEF@" -->
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The X Toolkit provides tools that simplify the design of
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application user interfaces in the X Window System programming environment.
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It assists application programmers by providing a set of common
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underlying user-interface functions. It also lets widget programmers
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modify existing widgets, by subclassing, or add new widgets. By using
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the X Toolkit in their applications, programmers can present a similar
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user interface across applications to all workstation users.
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</para>
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<para>
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<!-- .LP -->
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The X Toolkit consists of:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A set of Intrinsics functions for building widgets
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</para>
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</listitem>
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<listitem>
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<para>
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An architectural model for constructing widgets
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</para>
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</listitem>
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<listitem>
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<para>
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A widget set for application programming
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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While the majority of the Intrinsics functions are intended
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for the widget programmer,
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a subset of the Intrinsics functions are to be used by application programmers
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(see <emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis>).
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The architectural model lets the widget programmer design new widgets
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by using the Intrinsics and by combining other widgets.
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The application interface layers built on top of the X Toolkit include a
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coordinated set of widgets and composition policies.
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Some of these widgets and policies are specific to a single
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application domain, and others are common to a variety of
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applications.
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</para>
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<para>
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<!-- .LP -->
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The remainder of this chapter discusses the X Toolkit and Athena widget set:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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Terminology
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</para>
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</listitem>
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<listitem>
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<para>
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Model
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</para>
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</listitem>
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<listitem>
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<para>
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Conventions used in this manual
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</para>
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</listitem>
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<listitem>
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<para>
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Format of the Widget Reference Chapters
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</para>
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</listitem>
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</itemizedlist>
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</sect1>
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<sect1 id="Terminology">
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<title>Terminology</title>
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<para>
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<!-- .LP -->
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<!-- .XS -->
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<!-- Terminology -->
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<!-- .XE -->
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</para>
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<para>
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<!-- .LP -->
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In addition to the terms already defined for X programming (see
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<emphasis remap='I'>Xlib - C Language Interface</emphasis>),
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the following terms are specific to the Intrinsics and Athena widget set
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and used throughout this document.
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</para>
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<para>
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<!-- .LP -->
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<function>Application programmer</function>
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<!-- .IN "application programmer" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A programmer who uses the X Toolkit to produce an application user interface.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Child</function>
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<!-- .IN "child" "" "@DEF" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A widget that is contained within another "parent" widget.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Class</function>
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<!-- .IN "class" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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The general group to which a specific object belongs.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Client</function>
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<!-- .IN "client" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A function that uses a widget in an application or for composing
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other widgets.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>FullName</function>
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<!-- .IN "FullName" "" "@DEF" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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The name of a widget instance appended to the full name of its parent.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Instance</function>
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<!-- .IN "instance" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A specific widget object as opposed to a general widget class.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Method</function>
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<!-- .IN "method" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A function or procedure implemented by a widget class.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Name</function>
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<!-- .IN "name" "widget" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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The name that is specific to an instance of a widget for a given client.
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This name is specified at creation time and cannot be modified.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Object</function>
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<!-- .IN "object" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A data abstraction consisting of private data and private and public
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functions that operate on the private data.
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Users of the abstraction can interact with the object only through calls
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to the object's public functions.
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In the X Toolkit,
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some of the object's public functions are called directly by the application,
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while others are called indirectly when the application calls the common
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Intrinsics functions.
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In general, if a function is common to all widgets,
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an application uses a single Intrinsics function to invoke the function for all
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types of widgets.
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If a function is unique to a single widget type,
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the widget exports the function.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Parent</function>
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<!-- .IN "parent" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A widget that contains at least one other ("child") widget.
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A parent widget is also known as a composite widget.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Resource</function>
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<!-- .IN "resource" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A named piece of data in a widget that can be set by a client,
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by an application, or by user defaults.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Superclass</function>
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<!-- .IN "superclass" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A larger class of which a specific class is a member.
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All members of a class are also members of the superclass.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>User</function>
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<!-- .IN "user" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A person interacting with a workstation.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Widget</function>
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<!-- .IN "widget" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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An object providing a user-interface abstraction (for example, a Scrollbar
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widget).
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Widget class</function>
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<!-- .IN "widget class" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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The general group to which a specific widget belongs,
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otherwise known as the type of the widget.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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<!-- .LP -->
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<function>Widget programmer</function>
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<!-- .IN "widget programmer" "" "@DEF@" -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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A programmer who adds new widgets to the X Toolkit.
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</para>
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</listitem>
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</itemizedlist>
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</sect1>
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<sect1 id="Underlying_Model">
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<title>Underlying Model</title>
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<para>
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<!-- .LP -->
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<!-- .XS -->
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<!-- Underlying Model -->
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<!-- .XE -->
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<!-- .IN "underlying model" "" "@DEF@" -->
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The underlying architectural model is based on the following premises:
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<!-- .KS -->
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</para>
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<itemizedlist>
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<listitem>
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<para>
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</para>
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</listitem>
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<listitem>
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<para>
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Every user-interface widget is associated with an X window.
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The X window ID for a widget is readily available from the widget.
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Standard Xlib calls can be used by widgets for many of their input and
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output operations.
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<!-- .KE -->
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<!-- .KS -->
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</para>
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</listitem>
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<listitem>
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<para>
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</para>
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</listitem>
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<listitem>
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<para>
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The data for every widget is private to the widget and its subclasses.
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That is, the data is neither directly accessible
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nor visible outside of the module implementing the widget.
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All program interaction with the widget is performed by a set of operations
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(methods) that are defined for the widget.
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<!-- .KE -->
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<!-- .KS -->
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</para>
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</listitem>
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<listitem>
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<para>
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</para>
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</listitem>
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<listitem>
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<para>
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Widget semantics are clearly separated from widget layout geometry.
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Widgets are concerned with implementing specific user-interface
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semantics. They have little control over issues such as their size or
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placement relative to other widget peers. Mechanisms are provided for
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associating geometric managers with widgets and for widgets to make
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suggestions about their own geometry.
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<!-- .KE -->
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</para>
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</listitem>
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</itemizedlist>
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</sect1>
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<sect1 id="Conventions_Used_in_this_Manual">
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<title>Conventions Used in this Manual</title>
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<itemizedlist>
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<listitem>
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<para>
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<!-- .IN "conventions" "used in manual" "@DEF@" -->
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All resources available to the widgets are listed with each widget. Many
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of these are available to more than one widget class due to the object
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oriented nature of the Intrinsics. The new resources for each widget are
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listed in bold text, and the inherited resources are listed in plain text.
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</para>
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</listitem>
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<listitem>
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<para>
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Global symbols are printed in <function>bold</function> and can be function names,
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symbols defined in include files, or structure names. Arguments are
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printed in <emphasis remap='I'>italics</emphasis>.
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</para>
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</listitem>
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<listitem>
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<para>
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Each function is introduced by a general discussion that distinguishes
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it from other functions. The function declaration itself follows, and
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each argument is specifically explained. General discussion of the
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function, if any is required, follows the arguments. Where
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applicable, the last paragraph of the explanation lists the return values
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of the function.
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</para>
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</listitem>
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<listitem>
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<para>
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To eliminate any ambiguity between those arguments that you pass and
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those that a function returns to you, the explanations for all
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arguments that you pass start with the word <emphasis remap='I'>specifies</emphasis> or, in the
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case of multiple arguments, the word <emphasis remap='I'>specify</emphasis>. The explanations
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for all arguments that are returned to you start with the word
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<emphasis remap='I'>returns</emphasis> or, in the case of multiple arguments, the word
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<emphasis remap='I'>return</emphasis>. The explanations for all arguments that you can pass
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and are returned start with the words <emphasis remap='I'>specifies and returns</emphasis>.
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</para>
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</listitem>
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<listitem>
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<para>
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Any pointer to a structure that is used to return a value is
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designated as such by the <emphasis remap='I'>_return</emphasis> suffix as part of its name.
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All other pointers passed to these functions are used for reading
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only. A few arguments use pointers to structures that are used for
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both input and output and are indicated by using the <emphasis remap='I'>_in_out</emphasis>
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suffix.
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<!-- .IN "_return" "" "@DEF@" -->
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<!-- .IN "_in_out" "" "@DEF@" -->
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</para>
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</listitem>
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</itemizedlist>
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</sect1>
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<sect1 id="Format_of_the_Widget_Reference_Chapters">
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<title>Format of the Widget Reference Chapters</title>
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<para>
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<!-- .LP -->
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<!-- .IN "conventions" "chapter format" "@DEF@" -->
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<!-- .IN "chapter format" "" "@DEF@" -->
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The majority of this document is a reference guide for the Athena
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widget set. Chapters three through six give the programmer all
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information necessary to use the widgets. The layout of the chapters
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follows a specific pattern to allow the programmer to easily find the
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desired information.
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</para>
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<para>
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<!-- .LP -->
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The first few pages of every chapter give an overview of the widgets
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in that section. Widgets are grouped into chapters by functionality.
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<variablelist>
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<varlistentry>
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<term>
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"Chapter <!-- xref -->
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</term>
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<listitem>
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<para>
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Simple Widgets
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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"Chapter <!-- xref -->
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</term>
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<listitem>
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<para>
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Menus
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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"Chapter <!-- xref -->
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</term>
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<listitem>
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<para>
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Text Widgets
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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"Chapter <!-- xref -->
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</term>
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<listitem>
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<para>
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Composite and Constraint Widget
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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<!-- .LP -->
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Following the introduction will be a description of each widget in that
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chapter. When no functional grouping is obvious the widgets are listed
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in alphabetical order, such as in chapters three and six.
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</para>
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<para>
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<!-- .LP -->
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The first section of each widget's description is a table that
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contains general information about this widget class. Here is the
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table for the Box widget, and an explanation of all the entries.
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<literallayout class="monospaced">
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<!-- .TA 2.0i -->
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<!-- .ta 2.0i -->
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<!-- .sp -->
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Application Header file <X11/Xaw/Box.h>
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Class Header file <X11/Xaw/BoxP.h>
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Class boxWidgetClass
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Class Name Box
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Superclass Composite
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<!-- .sp -->
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</literallayout>
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<variablelist>
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<varlistentry>
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<term>
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<function>Application Header File</function>
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</term>
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<listitem>
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<para>
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<!-- .IN "application header file" "" "@DEF@" -->
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This file must be included when an application uses this widget.
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It usually contains the class definition, and some resource macros.
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This is often called the ``public'' header file.
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|
<!-- .IN "class header file" "" "@DEF@" -->
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
<function>Class Header File</function>
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This file will only be used by widget programmers. It will need to be
|
|
included by any widget that subclasses this widget. This is often
|
|
called the ``private'' header file.
|
|
<!-- .IN "class" "" "@DEF@" -->
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
<function>Class</function>
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This is the widget class of this widget. This global symbol is passed to
|
|
<function>XtCreateWidget</function> so that the Intrinsics will know which type of widget
|
|
to create.
|
|
<!-- .IN "class name" "" "@DEF@" -->
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
<function>Class Name</function>
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This is the resource name of this class. This name can be used in
|
|
a resource file to match any widget of this class.
|
|
<!-- .IN "superclass" "" -->
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
<function>Superclass</function>
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This is the superclass that this widget class is descended from. If
|
|
you understand how the superclass works it will allow you to more quickly
|
|
understand what this widget does, since much of its functionality may be
|
|
inherited from its superclass.
|
|
<!-- .sp -->
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
<para>
|
|
<!-- .LP -->
|
|
After this table follows a general description of the default behavior of
|
|
this widget, as seen by the user. In many cases this functionality
|
|
may be overridden by the application programmer, or by the user.
|
|
</para>
|
|
<para>
|
|
<!-- .LP -->
|
|
The next section is a table showing the
|
|
name, class, type and default value of each resource that is available
|
|
to this widget. There is also a column containing notes describing
|
|
special restrictions placed upon individual resources.
|
|
<!-- .IN "notes" "" "@DEF@" -->
|
|
<!-- .IN "A, note" "" "@DEF@" -->
|
|
<!-- .IN "D, note" "" "@DEF@" -->
|
|
<!-- .IN "C, note" "" "@DEF@" -->
|
|
<!-- .IN "R, note" "" "@DEF@" -->
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>
|
|
A
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This resource may be automatically adjusted when another
|
|
resource is changed.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
C
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This resource is only settable at widget creation time, and may not
|
|
be modified with <xref linkend='XtSetValues' xrefstyle='select: title'/>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
D
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
Do not modify this resource. While setting this resource will
|
|
work, it can cause unexpected behavior. When this symbol appears
|
|
there is another, preferred, interface provided by the X Toolkit.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
R
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
This resource is READ-ONLY, and may not be modified.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
<para>
|
|
<!-- .LP -->
|
|
After the resource table is a detailed description of every resource
|
|
available to that widget. Many of these are redundant, but printing
|
|
them with each widget saves page flipping. The names of the resources
|
|
that are inherited are printed in plain text, while the names of the
|
|
resources that are new to this class are printed in <function>bold</function>.
|
|
If you have already read the description of the superclass you need
|
|
only pay attention to the resources printed in bold.
|
|
</para>
|
|
<para>
|
|
<!-- .LP -->
|
|
For each composite widget there is a section on layout semantics that
|
|
follows the resource description. This section will describe the
|
|
effect of constraint resources on the layout of the children, as well
|
|
as a general description of where it prefers to place its children.
|
|
</para>
|
|
<para>
|
|
<!-- .LP -->
|
|
Descriptions of default translations and action routines come next, for
|
|
widgets to which they apply. The last item in each widget's
|
|
documentation is the description of all convenience routines provided by
|
|
the widget.
|
|
</para>
|
|
</sect1>
|
|
<sect1 id="Input_Focus">
|
|
<title>Input Focus</title>
|
|
<!-- .XS -->
|
|
<!-- Input Focus -->
|
|
<!-- .XE -->
|
|
<!-- .IN "input focus" "" "@DEF@" -->
|
|
<!-- .IN "input" "" "@DEF@" -->
|
|
<!-- .IN "XtNinput" "" "@DEF@" -->
|
|
<para>
|
|
<!-- .LP -->
|
|
The Intrinsics define a resource on all Shell widgets that interact with
|
|
the window manager called <function>input</function>. This resource requests the
|
|
assistance of window manager in acquiring the input focus. The
|
|
resource defaults to <function>False</function> in the Intrinsics, but is redefined to
|
|
default to <function>True</function> when an application is using the Athena widget
|
|
set. An application programmer may override this default and set the
|
|
resource back to <function>False</function> if the application does not need the window
|
|
manager to give it the input focus. See the
|
|
<emphasis remap='I'>X Toolkit Intrinsics - C Language Interface</emphasis> for details
|
|
on the <emphasis remap='I'>input</emphasis> resource.
|
|
|
|
</para>
|
|
</sect1>
|
|
</chapter>
|