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✏️ Editing: CH04.xml

<chapter id='Shell_Widgets'>
<title>Shell Widgets</title>

<para>
Shell widgets hold an application's top-level widgets to allow them to
communicate with the window manager and session manager.
Shells have been designed to be as nearly invisible as possible.
Clients have to create them,
but they should never have to worry about their sizes.
</para>

<para>
If a shell widget is resized from the outside (typically by a window manager),
the shell widget also resizes its managed child widget automatically.
Similarly, if the shell's child widget needs to change size,
it can make a geometry request to the shell,
and the shell negotiates the size change with the outer environment.
Clients should never attempt to change the size of their shells directly.
</para>

<para>The five types of public shells are:</para>
<variablelist>
  <varlistentry>
    <term>OverrideShell</term>
    <listitem>
      <para>
      Used for shell windows that completely bypass the window manager
      (for example, pop-up menu shells).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>TransientShell</term>
      <listitem>
        <para>Used for shell windows that have the
      <emphasis role='strong'>WM_TRANSIENT_FOR</emphasis>
      property set. The effect of this property is dependent upon the
      window manager being used.
        </para>
      </listitem>
  </varlistentry>
  <varlistentry>
      <term>TopLevelShell</term>
      <listitem>
        <para>Used for normal top-level windows
      (for example, any additional top-level widgets an application needs).
        </para>
      </listitem>
  </varlistentry>
  <varlistentry>
      <term>ApplicationShell</term>
      <listitem>
        <para>Formerly used for the single main top-level window that
      the window manager identifies as an application instance and
      made obsolete by SessionShell.
        </para>
      </listitem>
  </varlistentry>
  <varlistentry>
      <term>SessionShell</term>
      <listitem>
        <para>
      Used for the single main top-level window that
      the window manager identifies as an application instance and
      that interacts with the session manager.
        </para>
      </listitem>
  </varlistentry>
</variablelist>

<sect1 id="Shell_Widget_Definitions">
<title>Shell Widget Definitions</title>
<para>
Widgets negotiate their size and position with their parent widget,
that is, the widget that directly contains them.
Widgets at the top of the hierarchy do not have parent widgets.
Instead, they must deal with the outside world.
To provide for this,
each top-level widget is encapsulated in a special widget, called a
shell widget.
</para>

<para>
Shell
widgets, whose class is a subclass of the
Composite class,
encapsulate other widgets and can allow a widget to avoid the
geometry clipping imposed by the parent-child window relationship.
They also can provide a layer of communication with the window manager.
</para>

<para>The eight different types of shells are:</para>
<variablelist>
  <varlistentry>
    <term>Shell</term>
    <listitem>
      <para>The base class for shell widgets; provides the
      fields needed for all types of shells.  Shell
      is a direct subclass of
      <emphasis role='strong'>compositeWidgetClass</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>OverrideShell</term>
    <listitem>
      <para>A subclass of Shell; used for shell windows that completely
      bypass the window manager.</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>WMShell</term>
    <listitem>
      <para>A subclass of Shell; contains fields needed by the
      common window manager protocol.</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>VendorShell</term>
    <listitem>
      <para>A subclass of WMShell; contains fields used by
      vendor-specific window managers.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>TransientShell</term>
    <listitem>
      <para>A subclass of VendorShell; used for shell windows that
      desire the <emphasis role='strong'>WM_TRANSIENT_FOR</emphasis>
      property.</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>TopLevelShell</term>
    <listitem>
      <para>A subclass of VendorShell; used for normal top-level windows.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>ApplicationShell</term>
      <listitem>
      <para>A subclass of TopLevelShell; may be used for an application's additional
      root windows.</para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>SessionShell</term>
    <listitem>
      <para>A subclass of ApplicationShell; used for an application's
      main root window.</para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
Note that the classes
Shell,
WMShell,
and
VendorShell
are internal and should not be instantiated or subclassed.
Only
OverrrideShell,
TransientShell,
TopLevelShell,
ApplicationShell,
and
SessionShell
are intended for public use.
</para>

<sect2 id="ShellClassPart_Definitions">
<title>ShellClassPart Definitions</title>
<para>
Only the Shell
class has additional class fields, which are all contained in the
<function>ShellClassExtensionRec</function>.
None of the other Shell classes have any additional class fields:
</para>

<literallayout >
typedef struct {
        XtPointer extension;
} ShellClassPart, OverrideShellClassPart,
WMShellClassPart, VendorShellClassPart, TransientShellClassPart,
TopLevelShellClassPart, ApplicationShellClassPart, SessionShellClassPart;
</literallayout>

<para>The full Shell class record definitions are:</para>

<literallayout >
typedef struct _ShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
} ShellClassRec;
</literallayout>

<literallayout >
typedef struct {
	XtPointer	next_extension;	See <xref linkend='Class_Extension_Records' />
	XrmQuark	record_type;	See <xref linkend='Class_Extension_Records' />
	long	version;	See <xref linkend='Class_Extension_Records' />
	Cardinal	record_size;	See <xref linkend='Class_Extension_Records' />
	XtGeometryHandler	root_geometry_manager;	See below
} ShellClassExtensionRec, *ShellClassExtension;
</literallayout>

<literallayout >
typedef struct _OverrideShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	OverrideShellClassPart	override_shell_class;
} OverrideShellClassRec;
</literallayout>

<literallayout >
typedef struct _WMShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
} WMShellClassRec;
</literallayout>

<literallayout >
typedef struct _VendorShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
	VendorShellClassPart	vendor_shell_class;
} VendorShellClassRec;
</literallayout>

<literallayout >
typedef struct _TransientShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
	VendorShellClassPart	vendor_shell_class;
	TransientShellClassPart	transient_shell_class;
} TransientShellClassRec;
</literallayout>

<literallayout >
typedef struct _TopLevelShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
	VendorShellClassPart	vendor_shell_class;
	TopLevelShellClassPart	top_level_shell_class;
} TopLevelShellClassRec;
</literallayout>

<literallayout >
typedef struct _ApplicationShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
	VendorShellClassPart	vendor_shell_class;
	TopLevelShellClassPart	top_level_shell_class;
	ApplicationShellClassPart	application_shell_class;
} ApplicationShellClassRec;
</literallayout>

<literallayout >
typedef struct _SessionShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
	VendorShellClassPart	vendor_shell_class;
	TopLevelShellClassPart	top_level_shell_class;
	ApplicationShellClassPart	application_shell_class;
	SessionShellClassPart	session_shell_class;
} SessionShellClassRec;
</literallayout>

<para>
The single occurrences of the class records and pointers for creating
instances of shells are:
</para>

<literallayout >
extern ShellClassRec shellClassRec;
extern OverrideShellClassRec overrideShellClassRec;
extern WMShellClassRec wmShellClassRec;
extern VendorShellClassRec vendorShellClassRec;
extern TransientShellClassRec transientShellClassRec;
extern TopLevelShellClassRec topLevelShellClassRec;
extern ApplicationShellClassRec applicationShellClassRec;
extern SessionShellClassRec sessionShellClassRec;
extern WidgetClass shellWidgetClass;
extern WidgetClass overrideShellWidgetClass;
extern WidgetClass wmShellWidgetClass;
extern WidgetClass vendorShellWidgetClass;
extern WidgetClass transientShellWidgetClass;
extern WidgetClass topLevelShellWidgetClass;
extern WidgetClass applicationShellWidgetClass;
extern WidgetClass sessionShellWidgetClass;
</literallayout>

<para>
The following opaque types and opaque variables are defined
for generic operations on widgets whose class is a subclass of
Shell.
</para>

<informaltable frame='topbot'>
  <?dbfo keep-together="auto" ?>
  <tgroup cols='2' align='left' colsep='0' rowsep='0'>
  <colspec colwidth='1.0*' colname='c1'/>
  <colspec colwidth='1.0*' colname='c2'/>
  <thead>
    <row rowsep='1'>
      <entry>Types</entry>
      <entry>Variables</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry><emphasis role='strong'>ShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>shellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>OverrideShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>overrideShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>WMShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>wmShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>VendorShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>vendorShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>TransientShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>transientShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>TopLevelShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>topLevelShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>ApplicationShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>applicationShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>SessionShellWidget</emphasis></entry>
      <entry><emphasis role='strong'>sessionShellWidgetClass</emphasis></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>ShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>OverrideShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>WMShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>VendorShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>TransientShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>TopLevelShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>ApplicationShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
    <row>
      <entry><emphasis role='strong'>SessionShellWidgetClass</emphasis></entry>
      <entry></entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<para>
The declarations for all Intrinsics-defined shells except
VendorShell appear in
<function>Shell.h</function>
and
<function>ShellP.h</function>.
VendorShell has separate public and private .h files which are included by
<function>Shell.h</function>
and
<function>ShellP.h</function>.
</para>

<para>
<function>Shell.h</function>
uses incomplete structure definitions to ensure that the
compiler catches attempts to access private data in any of the Shell
instance or class data structures.
</para>

<para>
The symbolic constant for the
<function>ShellClassExtension</function>
version identifier is
<function>XtShellExtensionVersion</function>
(see <xref linkend='Class_Extension_Records' />).
</para>

<para>
The root_geometry_manager procedure acts as
the parent geometry manager for geometry requests made by shell
widgets.  When a shell widget calls either
<xref linkend='XtMakeGeometryRequest' xrefstyle='select: title'/>
or
<xref linkend='XtMakeResizeRequest' xrefstyle='select: title'/>,
the root_geometry_manager procedure is invoked to
negotiate the new geometry with the window manager.  If the window
manager permits the new geometry, the root_geometry_manager
procedure should
return
<function>XtGeometryYes</function>;
if the window manager denies the geometry
request or does not change the window geometry within some timeout
interval (equal to <emphasis remap='I'>wm_timeout</emphasis> in the case of WMShells), the
root_geometry_manager procedure should return
<function>XtGeometryNo</function>.
If the window manager makes some alternative geometry change, the
root_geometry_manager procedure may return either
<function>XtGeometryNo</function>
and handle the new geometry as a resize or
<function>XtGeometryAlmost</function>
in anticipation that the shell will accept the compromise.  If the
compromise is not accepted, the new size must then be handled as a
resize.  Subclasses of
Shell
that wish to provide their own
root_geometry_manager procedures are strongly encouraged to use enveloping to
invoke their superclass's root_geometry_manager procedure under most
situations, as the window manager interaction may be very complex.
</para>

<para>
If no
<function>ShellClassPart</function>
extension record is declared with <emphasis remap='I'>record_type</emphasis>
equal to
<emphasis role='strong'>NULLQUARK</emphasis>,
then
<function>XtInheritRootGeometryManager</function>
is assumed.
</para>
</sect2>

<sect2 id="ShellPart_Definition">
<title>ShellPart Definition</title>
<para>
The various shell widgets have the following additional instance
fields defined in
their widget records:
</para>

<literallayout >
typedef struct {
	String	geometry;
	XtCreatePopupChildProc	create_popup_child_proc;
	XtGrabKind	grab_kind;
	Boolean	spring_loaded;
	Boolean	popped_up;
	Boolean	allow_shell_resize;
	Boolean	client_specified;
	Boolean	save_under;
	Boolean	override_redirect;
	XtCallbackList	popup_callback;
	XtCallbackList	popdown_callback;
	Visual *	visual;
} ShellPart;
</literallayout>

<literallayout >
typedef struct {
	int	empty;
} OverrideShellPart;
</literallayout>

<literallayout >
typedef struct {
	String			title;
	int			wm_timeout;
	Boolean			wait_for_wm;
	Boolean			transient;
	Boolean			urgency;
	Widget			client_leader;
	String			window_role;
	struct _OldXSizeHints {
		long		flags;
		int		 x, y;
		int		width, height;
		int		min_width, min_height;
		int		max_width, max_height;
		int		width_inc, height_inc;
		struct {
			int	x;
			int	y;
		} min_aspect, max_aspect;
	} size_hints;
	XWMHints			wm_hints;
	int			base_width, base_height, win_gravity;
	Atom			title_encoding;
} WMShellPart;
</literallayout>

<literallayout >
typedef struct {
	int	vendor_specific;
} VendorShellPart;
</literallayout>

<literallayout >
typedef struct {
	Widget	transient_for;
} TransientShellPart;
typedef struct {
	String	icon_name;
	Boolean	iconic;
	Atom	icon_name_encoding;
} TopLevelShellPart;
</literallayout>

<literallayout >
typedef struct {
	char *	class;
	XrmClass	xrm_class;
	int	argc;
	char **	argv;
} ApplicationShellPart;
</literallayout>

<literallayout >
typedef struct {
	SmcConn	connection;
	String	session_id;
	String *	restart_command;
	String *	clone_command;
	String *	discard_command;
	String *	resign_command;
	String *	shutdown_command;
	String *	environment;
	String	current_dir;
	String	program_path;
	unsigned char	restart_style;
	Boolean	join_session;
	XtCallbackList	save_callbacks;
	XtCallbackList	interact_callbacks;
	XtCallbackList	cancel_callbacks;
	XtCallbackList	save_complete_callbacks;
	XtCallbackList	die_callbacks;
	XtCallbackList	error_callbacks;
} SessionShellPart;
</literallayout>

<para>
The full shell widget instance record definitions are:
</para>

<literallayout >
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
} ShellRec, *ShellWidget;
</literallayout>

<literallayout >
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	OverrideShellPart	override;
} OverrideShellRec, *OverrideShellWidget;
</literallayout>

<literallayout >
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
} WMShellRec, *WMShellWidget;
</literallayout>

<literallayout >
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
} VendorShellRec, *VendorShellWidget;
</literallayout>

<literallayout >
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TransientShellPart	transient;
} TransientShellRec, *TransientShellWidget;
</literallayout>

<literallayout >
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TopLevelShellPart	topLevel;
} TopLevelShellRec, *TopLevelShellWidget;
</literallayout>

<literallayout >
typedef  struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TopLevelShellPart	topLevel;
	ApplicationShellPart	application;
} ApplicationShellRec, *ApplicationShellWidget;
</literallayout>

<literallayout >
typedef  struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TopLevelShellPart	topLevel;
	ApplicationShellPart	application;
	SessionShellPart	session;
} SessionShellRec, *SessionShellWidget;
</literallayout>

</sect2>

<sect2 id="Shell_Resources">
<title>Shell Resources</title>
<para>
The resource names, classes, and representation types specified in
the
<function>shellClassRec</function>
resource list are:
</para>

<para>
OverrideShell
declares no additional resources beyond those defined by
Shell.
</para>

<para>
The resource names, classes, and representation types specified in
the
<function>wmShellClassRec</function>
resource list are:
</para>

<informaltable frame='topbot'>
  <?dbfo keep-together="always" ?>
  <tgroup cols='3' align='left' rowsep='0' colsep='0'>
  <colspec colwidth='1.0*' colname='c1'/>
  <colspec colwidth='1.0*' colname='c2'/>
  <colspec colwidth='1.0*' colname='c3'/>
  <thead>
    <row rowsep='1'>
      <entry>Name</entry>
      <entry>Class</entry>
      <entry>Representation</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>XtNbaseHeight</entry>
      <entry>XtCBaseHeight</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNbaseWidth</entry>
      <entry>XtCBaseWidth</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNclientLeader</entry>
      <entry>XtCClientLeader</entry>
      <entry>XtRWidget</entry>
    </row>
    <row>
      <entry>XtNheightInc</entry>
      <entry>XtCHeightInc</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNiconMask</entry>
      <entry>XtCIconMask</entry>
      <entry>XtRBitmap</entry>
    </row>
    <row>
      <entry>XtNiconPixmap</entry>
      <entry>XtCIconPixmap</entry>
      <entry>XtRBitmap</entry>
    </row>
    <row>
      <entry>XtNiconWindow</entry>
      <entry>XtCIconWindow</entry>
      <entry>XtRWindow</entry>
    </row>
    <row>
      <entry>XtNiconX</entry>
      <entry>XtCIconX</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNiconY</entry>
      <entry>XtCIconY</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNinitialState</entry>
      <entry>XtCInitialState</entry>
      <entry>XtRInitialState</entry>
    </row>
    <row>
      <entry>XtNinput</entry>
      <entry>XtCInput</entry>
      <entry>XtRBool</entry>
    </row>
    <row>
      <entry>XtNmaxAspectX</entry>
      <entry>XtCMaxAspectX</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNmaxAspectY</entry>
      <entry>XtCMaxAspectY</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNmaxHeight</entry>
      <entry>XtCMaxHeight</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNmaxWidth</entry>
      <entry>XtCMaxWidth</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNminAspectX</entry>
      <entry>XtCMinAspectX</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNminAspectY</entry>
      <entry>XtCMinAspectY</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNminHeight</entry>
      <entry>XtCMinHeight</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNminWidth</entry>
      <entry>XtCMinWidth</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNtitle</entry>
      <entry>XtCTitle</entry>
      <entry>XtRString</entry>
    </row>
    <row>
      <entry>XtNtitleEncoding</entry>
      <entry>XtCTitleEncoding</entry>
      <entry>XtRAtom</entry>
    </row>
    <row>
      <entry>XtNtransient</entry>
      <entry>XtCTransient</entry>
      <entry>XtRBoolean</entry>
    </row>
    <row>
      <entry>XtNwaitforwm, XtNwaitForWm</entry>
      <entry>XtCWaitforwm, XtCWaitForWm</entry>
      <entry>XtRBoolean</entry>
    </row>
    <row>
      <entry>XtNwidthInc</entry>
      <entry>XtCWidthInc</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNwindowRole</entry>
      <entry>XtCWindowRole</entry>
      <entry>XtRString</entry>
    </row>
    <row>
      <entry>XtNwinGravity</entry>
      <entry>XtCWinGravity</entry>
      <entry>XtRGravity</entry>
    </row>
    <row>
      <entry>XtNwindowGroup</entry>
      <entry>XtCWindowGroup</entry>
      <entry>XtRWindow</entry>
    </row>
    <row>
      <entry>XtNwmTimeout</entry>
      <entry>XtCWmTimeout</entry>
      <entry>XtRInt</entry>
    </row>
    <row>
      <entry>XtNurgency</entry>
      <entry>XtCUrgency</entry>
      <entry>XtRBoolean</entry>
    </row>
    <row>
      <entry>_</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<para>
The class resource list for
VendorShell
is implementation-defined.
</para>

<para>
The resource names, classes, and representation types that are specified in the
<function>transient\%ShellClassRec</function>
resource list are:
</para>

<para>
The resource names, classes, and representation types that are specified in the
<function>topLevelShellClassRec</function>
resource list are:
</para>

<para>
The resource names, classes, and representation types that are specified in the
<function>application\%ShellClassRec</function>
resource list are:
</para>

<para>
The resource names, classes, and representation types that are specified
in the
<function>sessionShellClassRec</function>
resource list are:
</para>

<informaltable frame='topbot'>
  <?dbfo keep-together="always" ?>
  <tgroup cols='3' align='left' colsep='0' rowsep='0'>
  <colspec colwidth='1.0*' colname='c1'/>
  <colspec colwidth='1.0*' colname='c2'/>
  <colspec colwidth='1.0*' colname='c3'/>
  <thead>
    <row rowsep='1'>
      <entry>Name</entry>
      <entry>Class</entry>
      <entry>Representation</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>XtNcancelCallback</entry>
      <entry>XtCCallback</entry>
      <entry>XtRCallback</entry>
    </row>
    <row>
      <entry>XtNcloneCommand</entry>
      <entry>XtCCloneCommand</entry>
      <entry>XtRCommandArgArray</entry>
    </row>
    <row>
      <entry>XtNconnection</entry>
      <entry>XtCConnection</entry>
      <entry>XtRSmcConn</entry>
    </row>
    <row>
      <entry>XtNcurrentDirectory</entry>
      <entry>XtCCurrentDirectory</entry>
      <entry>XtRDirectoryString</entry>
    </row>
    <row>
      <entry>XtNdieCallback</entry>
      <entry>XtCCallback</entry>
      <entry>XtRCallback</entry>
    </row>
    <row>
      <entry>XtNdiscardCommand</entry>
      <entry>XtCDiscardCommand</entry>
      <entry>XtRCommandArgArray</entry>
    </row>
    <row>
      <entry>XtNenvironment</entry>
      <entry>XtCEnvironment</entry>
      <entry>XtREnvironmentArray</entry>
    </row>
    <row>
      <entry>XtNerrorCallback</entry>
      <entry>XtCCallback</entry>
      <entry>XtRCallback</entry>
    </row>
    <row>
      <entry>XtNinteractCallback</entry>
      <entry>XtCCallback</entry>
      <entry>XtRCallback</entry>
    </row>
    <row>
      <entry>XtNjoinSession</entry>
      <entry>XtCJoinSession</entry>
      <entry>XtRBoolean</entry>
    </row>
    <row>
      <entry>XtNprogramPath</entry>
      <entry>XtCProgramPath</entry>
      <entry>XtRString</entry>
    </row>
    <row>
      <entry>XtNresignCommand</entry>
      <entry>XtCResignCommand</entry>
      <entry>XtRCommandArgArray</entry>
    </row>
    <row>
      <entry>XtNrestartCommand</entry>
      <entry>XtCRestartCommand</entry>
      <entry>XtRCommandArgArray</entry>
    </row>
    <row>
      <entry>XtNrestartStyle</entry>
      <entry>XtCRestartStyle</entry>
      <entry>XtRRestartStyle</entry>
    </row>
    <row>
      <entry>XtNsaveCallback</entry>
      <entry>XtCCallback</entry>
      <entry>XtRCallback</entry>
    </row>
    <row>
      <entry>XtNsaveCompleteCallback</entry>
      <entry>XtCCallback</entry>
      <entry>XtRCallback</entry>
    </row>
    <row>
      <entry>XtNsessionID</entry>
      <entry>XtCSessionID</entry>
      <entry>XtRString</entry>
    </row>
    <row>
      <entry>XtNshutdownCommand</entry>
      <entry>XtCShutdownCommand</entry>
      <entry>XtRCommandArgArray</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

</sect2>

<sect2 id="ShellPart_Default_Values">
<title>ShellPart Default Values</title>
<para>
The default values for fields common to all classes of public shells
(filled in by the
Shell
resource lists and the
Shell
initialize procedures) are:
</para>

<informaltable frame='topbot'>
  <?dbfo keep-together="always" ?>
  <tgroup cols='2' align='left' colsep='0' rowsep='0'>
  <colspec colwidth='1.0*' colname='c1'/>
  <colspec colwidth='1.0*' colname='c2'/>
  <thead>
    <row rowsep='1'>
      <entry>Field</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>geometry</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>create_popup_child_proc</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>grab_kind</entry>
      <entry>(none)</entry>
    </row>
    <row>
      <entry>spring_loaded</entry>
      <entry>(none)</entry>
    </row>
    <row>
      <entry>popped_up</entry>
      <entry><function>False</function></entry>
    </row>
    <row>
      <entry>allow_shell_resize</entry>
      <entry><function>False</function></entry>
    </row>
    <row>
      <entry>client_specified</entry>
      <entry>(internal)</entry>
    </row>
    <row>
      <entry>save_under</entry>
      <entry><function>True</function>
      for OverrideShell and TransientShell,
      <emphasis role='strong'>False</emphasis>
      otherwise</entry>
    </row>
    <row>
      <entry>override_redirect</entry>
      <entry><function>True</function>
      for OverrideShell,
      <function>False</function>
      otherwise</entry>
    </row>
    <row>
      <entry>popup_callback</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>popdown_callback</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>visual</entry>
      <entry><function>CopyFromParent</function></entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<para>
The <emphasis remap='I'>geometry</emphasis> field specifies the size and position
and is usually given only on a command line or in a defaults file.
If the <emphasis remap='I'>geometry</emphasis> field is non-NULL when
a widget of class WMShell
is realized, the geometry specification is parsed using
<function>XWMGeometry</function>
with a default geometry
string constructed from the values of <emphasis remap='I'>x</emphasis>, <emphasis remap='I'>y</emphasis>, <emphasis remap='I'>width</emphasis>,
<emphasis remap='I'>height</emphasis>, <emphasis remap='I'>width_inc</emphasis>,
and <emphasis remap='I'>height_inc</emphasis> and the size and position flags in the window manager
size hints are set.  If the geometry specifies an x or y position,
then
<function>USPosition</function>
is set.  If the geometry specifies a width or height, then
<function>USSize</function>
is set.  Any fields in the geometry specification
override the corresponding values in the
Core <emphasis remap='I'>x</emphasis>, <emphasis remap='I'>y</emphasis>, <emphasis remap='I'>width</emphasis>, and <emphasis remap='I'>height</emphasis> fields.
If <emphasis remap='I'>geometry</emphasis> is NULL or contains only a partial specification, then the
Core <emphasis remap='I'>x</emphasis>, <emphasis remap='I'>y</emphasis>, <emphasis remap='I'>width</emphasis>, and <emphasis remap='I'>height</emphasis> fields are used and
<function>PPosition</function>
and
<function>PSize</function>
are set as appropriate.
The geometry string is not copied by any of the Intrinsics
Shell classes; a client specifying the string in an arglist
or varargs list must ensure
that the value remains valid until the shell widget is realized.
For further information on the geometry string, see
<olink targetdoc='libX11' targetptr='Parsing_the_Window_Geometry' />
in <olink targetdoc='libX11' targetptr='libX11'>Xlib — C Language X Interface</olink>.
</para>

<para>
The <emphasis remap='I'>create_popup_child_proc</emphasis> procedure is called by the
<xref linkend='XtPopup' xrefstyle='select: title'/>
procedure and may remain NULL.
The <emphasis remap='I'>grab_kind</emphasis>, <emphasis remap='I'>spring_loaded</emphasis>,
and <emphasis remap='I'>popped_up</emphasis> fields maintain widget
state information as described under
<xref linkend='XtPopup' xrefstyle='select: title'/>,
<xref linkend='XtMenuPopup' xrefstyle='select: title'/>,
<xref linkend='XtPopdown' xrefstyle='select: title'/>,
and
<xref linkend='XtMenuPopdown' xrefstyle='select: title'/>.
The <emphasis remap='I'>allow_shell_resize</emphasis> field controls whether the widget contained
by the shell is allowed to try to resize itself.
If allow_shell_resize is
<function>False</function>,
any geometry requests made by the child will always return
<function>XtGeometryNo</function>
without interacting with the window manager.
Setting <emphasis remap='I'>save_under</emphasis>
<function>True</function>
instructs the server to attempt
to save the contents of windows obscured by the shell when it is mapped
and to restore those contents automatically when the shell is unmapped.
It is useful for pop-up menus.
Setting <emphasis remap='I'>override_redirect</emphasis>
<function>True</function>
determines
whether the window manager can intercede when the shell window
is mapped.
For further information on override_redirect,
see <olink targetdoc='libX11' targetptr='Window_Attributes' /> in
<olink targetdoc='libX11' targetptr='libX11'>Xlib — C Language X Interface</olink>
and
<olink targetdoc='icccm' targetptr='Pop_up_Windows' /> and
<olink targetdoc='icccm' targetptr='Redirection_of_Operations' /> in the
<olink targetdoc='icccm' targetptr='icccm'>Inter-Client Communication Conventions Manual</olink>.
The pop-up and pop-down callbacks are called during
<xref linkend='XtPopup' xrefstyle='select: title'/>
and
<xref linkend='XtPopdown' xrefstyle='select: title'/>.
The default value of the <emphasis remap='I'>visual</emphasis> resource is the symbolic value
<function>CopyFromParent</function>.
The Intrinsics do not need to query the parent's visual type when the
default value is used; if a client using
<xref linkend='XtGetValues' xrefstyle='select: title'/>
to examine the visual type receives the value
<function>CopyFromParent</function>,
it must then use
<function>XGetWindowAttributes</function>
if it needs the actual visual type.
</para>

<para>
The default values for Shell fields in
WMShell
and its subclasses are:
</para>

<informaltable frame='topbot'>
  <?dbfo keep-together="auto" ?>
  <tgroup cols='2' align='left' colsep='0' rowsep='0'>
  <colspec colwidth='1.0*' colname='c1'/>
  <colspec colwidth='1.0*' colname='c2'/>
  <thead>
    <row rowsep='1'>
      <entry>Field</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>title</entry>
      <entry>Icon name, if specified, otherwise the application's name</entry>
    </row>
    <row>
      <entry>wm_timeout</entry>
      <entry>Five seconds, in units of milliseconds</entry>
    </row>
    <row>
      <entry>wait_for_wm</entry>
      <entry><function>True</function></entry>
    </row>
    <row>
      <entry>transient</entry>
      <entry><function>True</function>
      for TransientShell,
      <function>False</function>
      otherwise</entry>
    </row>
    <row>
      <entry>urgency</entry>
      <entry><function>False</function></entry>
    </row>
    <row>
      <entry>client_leader</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>window_role</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>min_width</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>min_height</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>max_width</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>max_height</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>width_inc</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>height_inc</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>min_aspect_x</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>min_aspect_y</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>max_aspect_x</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>max_aspect_y</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>input</entry>
      <entry><function>False</function></entry>
    </row>
    <row>
      <entry>initial_state</entry>
      <entry>Normal</entry>
    </row>
    <row>
      <entry>icon_pixmap</entry>
      <entry>None</entry>
    </row>
    <row>
      <entry>icon_window</entry>
      <entry>None</entry>
    </row>
    <row>
      <entry>icon_x</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>icon_y</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>icon_mask</entry>
      <entry>None</entry>
    </row>
    <row>
      <entry>window_group</entry>
      <entry><function>XtUnspecifiedWindow</function></entry>
    </row>
    <row>
      <entry>base_width</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>base_height</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>win_gravity</entry>
      <entry><function>XtUnspecifiedShellInt</function></entry>
    </row>
    <row>
      <entry>title_encoding</entry>
      <entry>See text</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<para>
The <emphasis remap='I'>title</emphasis> and
<emphasis remap='I'>title_encoding</emphasis> fields are stored in the
<emphasis role='strong'>WM_NAME</emphasis>
property on the shell's window by the WMShell realize procedure.
If the <emphasis remap='I'>title_encoding</emphasis> field is
<function>None</function>,
the <emphasis remap='I'>title</emphasis> string is assumed to be in the encoding of the current
locale and the encoding of the
<emphasis role='strong'>WM_NAME</emphasis>
property is set to
<function>XStdICCTextStyle</function>.
If a language procedure has not been set
the default value of <emphasis remap='I'>title_encoding</emphasis> is
<emphasis role='strong'>XA_STRING</emphasis>, otherwise the default value is
<function>None</function>.
The <emphasis remap='I'>wm_timeout</emphasis> field specifies, in milliseconds,
the amount of time a shell is to wait for
confirmation of a geometry request to the window manager.
If none comes back within that time,
the shell assumes the window manager is not functioning properly
and sets <emphasis remap='I'>wait_for_wm</emphasis> to
<function>False</function>
(later events may reset this value).
When <emphasis remap='I'>wait_for_wm</emphasis> is
<function>False</function>,
the shell does not wait for a response, but relies on asynchronous
notification.
If <emphasis remap='I'>transient</emphasis> is
<function>True</function>,
the
<emphasis role='strong'>WM_TRANSIENT_FOR</emphasis>
property
will be stored on the shell window with a value as specified below.
The interpretation of this property is specific to the window manager
under which the application is run; see the
<olink targetdoc='icccm' targetptr='icccm'>Inter-Client Communication Conventions Manual</olink>
for more details.
</para>

<para>
The realize and set_values procedures of WMShell store the
<emphasis role='strong'>WM_CLIENT_LEADER</emphasis>
property on the shell window.
When <emphasis remap='I'>client_leader</emphasis> is not NULL and the client leader widget is
realized, the property will be created with the value of the window of the
client leader widget.
When <emphasis remap='I'>client_leader</emphasis> is NULL and the shell widget has a NULL parent,
the widget's window is used as the value of the
property.
When <emphasis remap='I'>client_leader</emphasis> is NULL and the shell widget has a non-NULL parent,
a search is made for the closest shell ancestor
with a non-NULL <emphasis remap='I'>client_leader</emphasis>,
and if none is found the shell ancestor with a NULL parent is the result.
If the resulting widget is realized, the property is created
with the value of the widget's window.
</para>

<para>
When the value of <emphasis remap='I'>window_role</emphasis> is not NULL, the
realize and set_values procedures store the
<emphasis role='strong'>WM_WINDOW_ROLE</emphasis>
property on the shell's window with the value of the resource.
</para>

<para>
All other resources specify fields in the window manager hints
and the window manager size hints.
The realize and set_values procedures of
WMShell
set the corresponding flag bits in the
hints if any of the fields contain nondefault values.  In addition, if
a flag bit is set that refers to a field with the value
<function>XtUnspecifiedShellInt</function>,
the value of the field is modified as follows:
</para>

<para>
If the shell widget has a non-NULL parent, then the
realize and set_values procedures replace the value
<function>XtUnspecifiedWindow</function>
in the <emphasis remap='I'>window_group</emphasis> field with the window id of the root widget
of the widget tree if the
root widget is realized. The symbolic constant
<function>XtUnspecifiedWindowGroup</function>
may be used to indicate that the <emphasis remap='I'>window_group</emphasis> hint flag bit is not
to be set.  If <emphasis remap='I'>transient</emphasis> is
<function>True</function>,
the shell's class is not a subclass of
TransientShell,
and <emphasis remap='I'>window_group</emphasis> is not
<function>XtUnspecifiedWindowGroup</function>,
the WMShell realize and set_values procedures then store the
<emphasis role='strong'>WM_TRANSIENT_FOR</emphasis>
property with the value of <emphasis remap='I'>window_group</emphasis>.
</para>

<para>
Transient
shells have the following additional resource:
</para>

<para>
The realize and set_values procedures of
TransientShell
store the
<emphasis role='strong'>WM_TRANSIENT_FOR</emphasis>
property on the shell window if <emphasis remap='I'>transient</emphasis> is
<function>True</function>.
If <emphasis remap='I'>transient_for</emphasis> is non-NULL and the widget specified by
<emphasis remap='I'>transient_for</emphasis> is realized, then its window is used as the value of the
<emphasis role='strong'>WM_TRANSIENT_FOR</emphasis>
property; otherwise, the value of <emphasis remap='I'>window_group</emphasis> is used.
</para>

<para>
<function>TopLevel</function>
shells have the the following additional resources:
</para>

<para>
The <emphasis remap='I'>icon_name</emphasis>
and <emphasis remap='I'>icon_name_encoding</emphasis> fields are stored in the
<emphasis role='strong'>WM_ICON_NAME</emphasis>
property on the shell's window by the TopLevelShell realize
procedure.
If the <emphasis remap='I'>icon_name_encoding</emphasis> field is
<function>None</function>,
the <emphasis remap='I'>icon_name</emphasis> string is assumed to be in the encoding of the
current locale and the encoding of the
<emphasis role='strong'>WM_ICON_NAME</emphasis>
property is set to
<function>XStdICCTextStyle</function>.
If a language procedure has not been set,
the default value of <emphasis remap='I'>icon_name_encoding</emphasis> is
<emphasis role='strong'>XA_STRING</emphasis>, otherwise the default value is
<function>None</function>.
The <emphasis remap='I'>iconic</emphasis> field may be used by a client to request
that the window manager iconify or deiconify the shell; the
TopLevelShell
set_values procedure will send the appropriate
<emphasis role='strong'>WM_CHANGE_STATE</emphasis>
message (as specified by the <emphasis remap='I'>Inter-Client Communication Conventions Manual</emphasis>)
if this resource is changed from
<function>False</function>
to
<function>True</function>
and will call
<xref linkend='XtPopup' xrefstyle='select: title'/>
specifying <emphasis remap='I'>grab_kind</emphasis> as
<function>XtGrabNone</function>
if <emphasis remap='I'>iconic</emphasis> is changed from
<function>True</function>
to
<function>False</function>.
The XtNiconic resource is also an alternative way to set
the XtNinitialState resource
to indicate that a shell should be initially displayed as an icon; the
TopLevelShell
initialize procedure will set <emphasis remap='I'>initial_state</emphasis> to
<function>IconicState</function>
if <emphasis remap='I'>iconic</emphasis> is
<function>True</function>.
</para>

<para>
Application
shells have the following additional resources:
</para>

<para>
The <emphasis remap='I'>argc</emphasis> and <emphasis remap='I'>argv</emphasis> fields are used to initialize
the standard property
<emphasis role='strong'>WM_COMMAND</emphasis>.  See the
<olink targetdoc='icccm' targetptr='icccm'>Inter-Client Communication Conventions Manual</olink>
for more information.
</para>

<para>
The default values for the SessionShell instance fields,
which are filled in from the resource lists and by the
initialize procedure, are
</para>

<informaltable frame='topbot'>
  <?dbfo keep-together="always" ?>
  <tgroup cols='2' align='left' colsep='0' rowsep='0'>
  <colspec colwidth='1.0*' colname='c1'/>
  <colspec colwidth='1.0*' colname='c2'/>
  <thead>
    <row rowsep='1'>
      <entry>Field</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>cancel_callbacks</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>clone_command</entry>
      <entry>See text</entry>
    </row>
    <row>
      <entry>connection</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>current_dir</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>die_callbacks</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>discard_command</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>environment</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>error_callbacks</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>interact_callbacks</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>join_session</entry>
      <entry><emphasis role='strong'>True</emphasis></entry>
    </row>
    <row>
      <entry>program_path</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>resign_command</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>restart_command</entry>
      <entry>See text</entry>
    </row>
    <row>
      <entry>restart_style</entry>
      <entry><emphasis role='strong'>SmRestartIfRunning</emphasis></entry>
    </row>
    <row>
      <entry>save_callbacks</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>save_complete_callbacks</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>session_id</entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>shutdown_command</entry>
      <entry>NULL</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<para>
The <emphasis remap='I'>connection</emphasis> field contains the session connection object or NULL
if a session connection is not being managed by this widget.
</para>

<para>
The <emphasis remap='I'>session_id</emphasis> is an identification assigned to the session
participant by the session manager.
The <emphasis remap='I'>session_id</emphasis> will be passed to the session
manager as the client identifier of the previous session.
When a connection is established with the session manager,
the client id assigned by the session manager is stored
in the <emphasis remap='I'>session_id</emphasis> field.
When not NULL, the <emphasis remap='I'>session_id</emphasis> of the Session shell widget that
is at the root of the widget tree of the client leader widget will be
used to create the
<emphasis role='strong'>SM_CLIENT_ID</emphasis>
property on the client leader's window.
</para>

<para>
If <emphasis remap='I'>join_session</emphasis> is
<function>False</function>,
the widget will not attempt to establish a
connection to the session manager at shell creation time.
See <xref linkend='Joining_a_Session' /> and
<xref linkend='Resigning_from_a_Session' />
for more information on the functionality of this resource.
</para>

<para>
The <emphasis remap='I'>restart_command</emphasis>, <emphasis remap='I'>clone_command</emphasis>, <emphasis remap='I'>discard_command</emphasis>,
<emphasis remap='I'>resign_command</emphasis>, <emphasis remap='I'>shutdown_command</emphasis>, <emphasis remap='I'>environment</emphasis>,
<emphasis remap='I'>current_dir</emphasis>, <emphasis remap='I'>program_path</emphasis>, and
<emphasis remap='I'>restart_style</emphasis> fields contain standard session properties.
</para>

<para>
When a session connection is established or newly managed by the shell,
the shell initialize and set_values methods check the values of the
<emphasis remap='I'>restart_command</emphasis>,
<emphasis remap='I'>clone_command</emphasis>,
and <emphasis remap='I'>program_path</emphasis>
resources.  At that time, if <emphasis remap='I'>restart_command</emphasis> is NULL, the value
of the <emphasis remap='I'>argv</emphasis> resource will be copied to <emphasis remap='I'>restart_command</emphasis>.
Whether or not <emphasis remap='I'>restart_command</emphasis> was NULL,
if "<emphasis>-xtsessionID</emphasis>" "<emphasis>&lt;session id&gt;</emphasis>" does not
already appear in the <emphasis remap='I'>restart_command</emphasis>, it will be added by the
initialize and set_values methods at the beginning of the command arguments;
if the "<emphasis>-xtsessionID</emphasis>" argument already appears with an incorrect
<emphasis>session id</emphasis> in the following argument, that argument
will be replaced with the current <emphasis>session id</emphasis>.
</para>

<para>
After this, the shell initialize and set_values procedures check the
<emphasis remap='I'>clone_command</emphasis>.  If <emphasis remap='I'>clone_command</emphasis> is NULL,
<emphasis remap='I'>restart_command</emphasis> will be copied to <emphasis remap='I'>clone_command</emphasis>,
except the "<emphasis>-xtsessionID</emphasis>" and following argument will not be copied.
</para>

<para>
Finally, the shell initialize and set_values procedures check the
<emphasis remap='I'>program_path</emphasis>.  If <emphasis remap='I'>program_path</emphasis> is NULL, the
first element of <emphasis remap='I'>restart_command</emphasis> is copied to <emphasis remap='I'>program_path</emphasis>.
</para>

<para>
The possible values of <emphasis remap='I'>restart_style</emphasis> are
<function>SmRestartIfRunning</function>,
<function>SmRestartAnyway</function>,
<function>SmRestartImmediately</function>,
and
<function>SmRestartNever</function>.
A resource converter is registered for this resource;
for the strings that it recognizes,
see <xref linkend='Predefined_Resource_Converters' />.
</para>

<para>
The resource type EnvironmentArray is a NULL-terminated array of
pointers to strings;
each string has the format "name=value".
The `=' character may not appear in the name,
and the string is terminated by a null character.
</para>
</sect2>
</sect1>

<sect1 id="Session_Participation">
<title>Session Participation</title>
<para>
Applications can participate in a user's session, exchanging messages
with the session manager as described in the
<emphasis>X Session Management Protocol</emphasis> and the
<emphasis remap='I'>X Session Management Library</emphasis>.
</para>

<para>
When a widget of
<function>sessionShellWidgetClass</function>
or a subclass is created, the widget provides support for the application
as a session participant and continues to provide support until the
widget is destroyed.
</para>

<sect2 id="Joining_a_Session">
<title>Joining a Session</title>
<para>
When a Session shell is created,
if <emphasis remap='I'>connection</emphasis> is NULL,
and if <emphasis remap='I'>join_session</emphasis> is
<function>True</function>,
and if <emphasis remap='I'>argv</emphasis> or <emphasis remap='I'>restart_command</emphasis> is not NULL,
and if in POSIX environments the
<emphasis role='strong'>SESSION_MANAGER</emphasis>
environment variable is defined,
the shell will attempt to establish a new connection with the session manager.
</para>

<para>
To transfer management of an existing session connection from an
application to the shell at widget creation time, pass the existing
session connection ID as the <emphasis remap='I'>connection</emphasis> resource value
when creating the Session shell,
and if the other creation-time conditions on session participation are met,
the widget will maintain the connection with the session manager.
The application must ensure that only one
Session shell manages the connection.
</para>

<para>
In the Session shell set_values procedure,
if <emphasis remap='I'>join_session</emphasis> changes from
<function>False</function>
to
<function>True</function>
and <emphasis remap='I'>connection</emphasis> is NULL and when in POSIX environments the
<emphasis role='strong'>SESSION_MANAGER</emphasis>
environment variable is defined,
the shell will attempt to open a connection to the session manager.
If <emphasis remap='I'>connection</emphasis> changes from NULL to non-NULL, the
Session shell
will take over management of that session connection and will set
<emphasis remap='I'>join_session</emphasis> to
<function>True</function>.
If <emphasis remap='I'>join_session</emphasis> changes from
<function>False</function>
to
<function>True</function>
and <emphasis remap='I'>connection</emphasis> is not NULL, the
Session shell will take over management of the session connection.
</para>

<para>
When a successful connection has been established, <emphasis remap='I'>connection</emphasis>
contains the session connection ID for the session participant.
When the shell begins to manage the connection, it will call
<xref linkend='XtAppAddInput' xrefstyle='select: title'/>
to register the handler which watches for protocol messages
from the session manager.
When the attempt to connect fails, a warning message is issued
and <emphasis remap='I'>connection</emphasis> is set to NULL.
</para>

<para>
While the connection is being managed, if a
<function>SaveYourself</function>,
<function>SaveYourselfPhase2</function>,
<function>Interact</function>,
<function>ShutdownCancelled</function>,
<function>SaveComplete</function>,
or
<function>Die</function>
message is received from the session manager, the Session shell will
call out to application callback procedures registered
on the respective callback list of the Session shell and will
send
<function>SaveYourselfPhase2Request</function>,
<function>InteractRequest</function>,
<function>InteractDone</function>,
<function>SaveYourselfDone</function>,
and
<function>ConnectionClosed</function>
messages as appropriate.
Initially, all of the client's session properties are undefined.
When any of the session property resource values are defined or change,
the Session shell initialize and set_values procedures
will update the client's session property value by a
<function>SetProperties</function>
or a
<function>DeleteProperties</function>
message, as appropriate.
The session ProcessID and UserID properties are always set by the shell
when it is possible to determine the value of these properties.
</para>
</sect2>

<sect2 id="Saving_Application_State">
<title>Saving Application State</title>
<para>
The session manager instigates an application checkpoint by sending a
<function>SaveYourself</function>
request.
Applications are responsible for saving their state in response to the
request.
</para>

<para>
When the
<function>SaveYourself</function>
request arrives, the procedures registered on the
Session shell's save callback list are called.
If the application does not register any save callback procedures on
the save callback list, the shell will report to the session manager
that the application failed to save its state.
Each procedure on the save callback list receives a token
in the <emphasis remap='I'>call_data</emphasis> parameter.
</para>

<para>
The checkpoint token in the <emphasis remap='I'>call_data</emphasis> parameter is of type
<function>XtCheckpointToken</function>.
</para>

<literallayout >
typedef struct {
	int	save_type;
	int	interact_style;
	Boolean	shutdown;
	Boolean	fast;
	Boolean	cancel_shutdown
	int	phase;
	int	interact_dialog_type;	/* return */
	Boolean	request_cancel;	/* return */
	Boolean	request_next_phase;	/* return */
	Boolean	save_success;	/* return */
} XtCheckpointTokenRec, *XtCheckpointToken;
</literallayout>

<para>
The <emphasis remap='I'>save_type</emphasis>, <emphasis remap='I'>interact_style</emphasis>, <emphasis remap='I'>shutdown</emphasis>, and <emphasis remap='I'>fast</emphasis>
fields of the token contain the parameters of the
<function>SaveYourself</function>
message.
The possible values of <emphasis remap='I'>save_type</emphasis> are
<function>SmSaveLocal</function>,
<function>SmSaveGlobal</function>,
and
<function>SmSaveBoth</function>;
these indicate the type of information to be saved.
The possible values of <emphasis remap='I'>interact_style</emphasis> are
<function>SmInteractStyleNone</function>,
<function>SmInteractStyleErrors</function>,
and
<function>SmInteractStyleAny</function>;
these indicate whether user interaction would be permitted
and, if so, what kind of interaction.
If <emphasis remap='I'>shutdown</emphasis> is
<function>True</function>,
the checkpoint is being performed in preparation for the end of the session.
If <emphasis remap='I'>fast</emphasis> is
<function>True</function>,
the client should perform the checkpoint as quickly as possible.
If <emphasis remap='I'>cancel_shutdown</emphasis> is
<function>True</function>,
a
<function>ShutdownCancelled</function>
message has been received for the current save operation. 
(See <xref linkend='Resigning_from_a_Session' />.)
The <emphasis remap='I'>phase</emphasis> is used by manager clients, such as a window manager,
to distinguish between the first and second phase of a save operation.
The <emphasis remap='I'>phase</emphasis> will be either 1 or 2.
The remaining fields in the checkpoint token structure are provided for
the application to communicate with the shell.
</para>

<para>
Upon entry to the first application save callback procedure, the return
fields in the token have the following initial values:
<emphasis remap='I'>interact_dialog_type</emphasis> is
<function>SmDialogNormal</function>;
<emphasis remap='I'>request_cancel</emphasis> is
<function>False</function>;
<emphasis remap='I'>request_next_phase</emphasis> is
<function>False</function>;
and <emphasis remap='I'>save_success</emphasis> is
<function>True</function>.
When a token is returned with any of the four return fields containing
a noninitial value, and when the field is applicable, subsequent tokens
passed to the application during the current save operation
will always contain the noninitial value.
</para>

<para>
The purpose of the token's <emphasis remap='I'>save_success</emphasis> field is to
indicate the outcome of the entire operation to the
session manager and ultimately, to the user.
Returning
<function>False</function>
indicates some portion of the application state
could not be successfully saved.  If any token is returned
to the shell with <emphasis remap='I'>save_success</emphasis>
<function>False</function>,
tokens subsequently received
by the application for the current save operation will show
<emphasis remap='I'>save_success</emphasis> as
<function>False</function>.
When the shell sends the final status of the checkpoint to the
session manager, it will indicate failure to save application state
if any token was returned with <emphasis remap='I'>save_success</emphasis>
<function>False</function>.
</para>

<para>
Session participants that manage and save the state of other clients
should structure their save or interact callbacks to
set <emphasis remap='I'>request_next_phase</emphasis> to
<function>True</function>
when phase is 1, which will cause the shell to send the
<function>SaveYourselfPhase2Request</function>
when the first phase is complete.  When the
<function>SaveYourselfPhase2</function>
message is received, the shell will invoke the save callbacks a
second time with <emphasis remap='I'>phase</emphasis> equal to 2.
Manager clients should save the state of other clients
when the callbacks are invoked the second time and <emphasis remap='I'>phase</emphasis> equal to 2.
</para>

<para>
The application may request additional tokens while a checkpoint is under way,
and these additional tokens must be returned by an explicit call.
</para>

<para>
To request an additional token for a save callback response that has a
deferred outcome, use
<xref linkend='XtSessionGetToken' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtSessionGetToken'>
<funcprototype>
<funcdef>XtCheckpointToken <function>XtSessionGetToken</function></funcdef>
   <paramdef>Widget <parameter>widget</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>widget</emphasis>
    </term>
    <listitem>
      <para>
Specifies the Session shell widget which manages session participation.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The
<xref linkend='XtSessionGetToken' xrefstyle='select: title'/>
function will return NULL if no checkpoint operation is currently under way.
</para>

<para>
To indicate the completion of checkpoint processing including user
interaction, the application must signal the Session shell
by returning all tokens.
(See <xref linkend='Interacting_with_the_User_during_a_Checkpoint' /> and 
<xref linkend='Completing_a_Save' />).
To return a token, use
<xref linkend='XtSessionReturnToken' xrefstyle='select: title'/>.
</para>

<funcsynopsis id='XtSessionReturnToken'>
<funcprototype>
<funcdef>void <function>XtSessionReturnToken</function></funcdef>
   <paramdef>XtCheckpointToken <parameter>token</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>token</emphasis>
    </term>
    <listitem>
      <para>
Specifies a token that was received as the <emphasis remap='I'>call_data</emphasis> by a procedure
on the interact callback list or a token that was received by a call to
<xref linkend='XtSessionGetToken' xrefstyle='select: title'/>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
Tokens passed as <emphasis remap='I'>call_data</emphasis> to save callbacks are implicitly
returned when the save callback procedure returns.
A save callback procedure should not call
<xref linkend='XtSessionReturnToken' xrefstyle='select: title'/>
on the token passed in its <emphasis remap='I'>call_data</emphasis>.
</para>

<sect3 id="Requesting_Interaction">
<title>Requesting Interaction</title>
<para>
When the token <emphasis remap='I'>interact_style</emphasis> allows user interaction,
the application may
interact with the user during the checkpoint, but must wait for permission
to interact.
Applications request permission to interact with the user during the
checkpointing operation by registering a procedure on the Session
shell's interact callback list.  When all save callback procedures have
returned, and each time a token that was granted by a call to
<xref linkend='XtSessionGetToken' xrefstyle='select: title'/>
is returned, the Session shell examines the interact callback list.
If interaction is permitted and the interact callback list is not empty,
the shell will send an
<function>InteractRequest</function>
to the session manager when an interact request is not already outstanding
for the application.
</para>

<para>
The type of interaction dialog that will be requested is specified by
the <emphasis remap='I'>interact_dialog_type</emphasis> field in the checkpoint token.
The possible values for <emphasis remap='I'>interact_dialog_type</emphasis> are
<function>SmDialogError</function>
and
<function>SmDialogNormal</function>.
If a token is returned with <emphasis remap='I'>interact_dialog_type</emphasis> containing
<function>SmDialogError</function>,
the interact request and any subsequent interact requests will be for
an error dialog; otherwise, the request will be for a normal dialog with
the user.
</para>

<para>
When a token is returned with <emphasis remap='I'>save_success</emphasis>
<function>False</function>
or <emphasis remap='I'>interact_dialog_type</emphasis>
<function>SmDialogError</function>,
tokens subsequently passed to callbacks during the same active
<function>SaveYourself</function>
response will reflect these changed values, indicating that
an error condition has occurred during the checkpoint.
</para>

<para>
The <emphasis remap='I'>request_cancel</emphasis> field is a return value for interact callbacks only.
Upon return from a procedure on the save callback list, the value
of the token's <emphasis remap='I'>request_cancel</emphasis> field is not examined by the shell.
This is also true of tokens received through a call to
<xref linkend='XtSessionGetToken' xrefstyle='select: title'/>.
</para>
</sect3>

<sect3 id="Interacting_with_the_User_during_a_Checkpoint">
<title>Interacting with the User during a Checkpoint</title>
<para>
When the session manager grants the application's request for user interaction,
the Session shell receives an
<function>Interact</function>
message.
The procedures registered on the interact callback list are executed,
but not as if executing a typical callback list.
These procedures are individually executed in
sequence, with a checkpoint token functioning as the sequencing mechanism.
Each step in the sequence begins by removing a procedure
from the interact callback list
and executing it with a token passed in the <emphasis remap='I'>call_data</emphasis>.
The interact callback will typically pop up a dialog box and return.
When the user interaction and associated application checkpointing has
completed, the application must return the token by calling
<xref linkend='XtSessionReturnToken' xrefstyle='select: title'/>.
Returning the token completes the current step and triggers the next step
in the sequence.
</para>

<para>
During interaction the client may request cancellation of a shutdown.
When a token passed as <emphasis remap='I'>call_data</emphasis> to an interact procedure is returned,
if <emphasis remap='I'>shutdown</emphasis> is
<function>True</function>
and <emphasis remap='I'>cancel_shutdown</emphasis> is
<function>False</function>,
<emphasis remap='I'>request_cancel</emphasis> indicates whether the
application requests that the pending shutdown be cancelled.
If <emphasis remap='I'>request_cancel</emphasis> is
<function>True</function>,
the field will also be
<function>True</function>
in any tokens subsequently granted during the checkpoint operation.
When a token is returned requesting cancellation of
the session shutdown, pending interact procedures will still be
called by the Session shell.
When all interact procedures have been removed from the interact callback
list, executed, and the final interact token returned to the shell, an
<function>InteractDone</function>
message is sent to the session manager, indicating whether
a pending session shutdown is requested to be cancelled.
</para>
</sect3>

<sect3 id="Responding_to_a_Shutdown_Cancellation">
<title>Responding to a Shutdown Cancellation</title>
<para>
Callbacks registered on the cancel callback list are invoked when the
Session shell processes a
<function>ShutdownCancelled</function>
message from the session manager.  This may occur during the
processing of save callbacks, while waiting for interact permission,
during user interaction, or after the save operation is complete and
the application is expecting a
<function>SaveComplete</function>
or a
<function>Die</function>
message.
The <emphasis remap='I'>call_data</emphasis> for these callbacks is NULL.
</para>

<para>
When the shell notices that a pending shutdown has been cancelled,
the token <emphasis remap='I'>cancel_shutdown</emphasis> field will be
<function>True</function>
in tokens subsequently given to the application.
</para>

<para>
Receiving notice of a shutdown cancellation does not cancel the
pending execution of save callbacks or interact callbacks.
After the cancel callbacks execute, if <emphasis remap='I'>interact_style</emphasis> is not
<function>SmInteractStyleNone</function>
and the interact list is not empty,
the procedures on the interact callback list will be executed
and passed a token with <emphasis remap='I'>interact_style</emphasis>
<function>SmInteractStyleNone</function>.
The application should not interact with the user, and the Session shell
will not send an
<function>InteractDone</function>
message.
</para>
</sect3>

<sect3 id="Completing_a_Save">
<title>Completing a Save</title>
<para>
When there is no user interaction, the shell regards the application
as having finished saving state when all callback procedures
on the save callback list have returned, and any additional tokens
passed out by
<xref linkend='XtSessionGetToken' xrefstyle='select: title'/>
have been returned by corresponding calls to
<xref linkend='XtSessionReturnToken' xrefstyle='select: title'/>.
If the save operation involved user interaction,
the above completion conditions apply, and in addition, all requests for
interaction have been granted or cancelled,
and all tokens passed to interact callbacks have been returned
through calls to
<xref linkend='XtSessionReturnToken' xrefstyle='select: title'/>.
If the save operation involved a manager client that requested the
second phase, the above conditions apply to both the first and second
phase of the save operation.
</para>

<para>
When the application has finished saving state,
the Session shell will report the result to the session manager by
sending the
<function>SaveYourselfDone</function>
message.
If the session is continuing, the shell will receive the
<function>SaveComplete</function>
message when all applications have completed saving state.
This message indicates that applications may again allow changes
to their state.  The shell will execute the save_complete callbacks.
The <emphasis remap='I'>call_data</emphasis> for these callbacks is NULL.
</para>
</sect3>
</sect2>

<sect2 id="Responding_to_a_Shutdown">
<title>Responding to a Shutdown</title>
<para>
Callbacks registered on the die callback list are invoked when the
session manager sends a
<function>Die</function>
message.
The callbacks on this list should do whatever is appropriate to quit
the application.
Before executing procedures on the die callback list,
the Session shell will close the connection to the session manager
and will remove the handler that watches for protocol messages.
The <emphasis remap='I'>call_data</emphasis> for these callbacks is NULL.
</para>
</sect2>

<sect2 id="Resigning_from_a_Session">
<title>Resigning from a Session</title>
<para>
When the Session shell widget is destroyed, the destroy method will
close the connection to the session manager by sending a
<function>ConnectionClosed</function>
protocol message and will remove the input callback
that was watching for session protocol messages.
</para>

<para>
When
<xref linkend='XtSetValues' xrefstyle='select: title'/>
is used to set <emphasis remap='I'>join_session</emphasis> to
<function>False</function>,
the set_values method of the Session shell will close the
connection to the session manager if one exists by sending a
<function>ConnectionClosed</function>
message, and <emphasis remap='I'>connection</emphasis> will be set to NULL.
</para>

<para>
Applications that exit in response to user actions and that do not
wait for phase 2 destroy to complete on
the Session shell should set <emphasis remap='I'>join_session</emphasis> to
<function>False</function>
before exiting.
</para>

<para>
When
<xref linkend='XtSetValues' xrefstyle='select: title'/>
is used to set <emphasis remap='I'>connection</emphasis> to NULL,
the Session shell will stop managing the connection, if one exists.
However, that session connection will not be closed.
</para>

<para>
Applications that wish to ensure continuation of a session connection
beyond the destruction of the shell should first retrieve the
<emphasis remap='I'>connection</emphasis> resource value,
then set the <emphasis remap='I'>connection</emphasis> resource to NULL,
and then they may safely destroy the widget without losing control
of the session connection.
</para>

<para>
The error callback list will be called if an unrecoverable
communications error occurs while the shell is managing the connection.
The shell will close the connection, set <emphasis remap='I'>connection</emphasis> to NULL,
remove the input callback, and
call the procedures registered on the error callback list.
The <emphasis remap='I'>call_data</emphasis> for these callbacks is NULL.
</para>
</sect2>
</sect1>
</chapter>

MR SKB