path: root/libXt/specs/CH04

.\" $Xorg: CH04,v 1.3 2000/08/17 19:42:44 cpqbld Exp $
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.\" Copyright \(co 1985, 1986, 1987, 1988, 1991, 1994
.\" Digital Equipment Corporation, Maynard, Massachusetts.
.\" 
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.\" purpose and without fee is hereby granted, provided that the above copyright
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\&
.sp 1
.ce 3
\s+1\fBChapter 4\fP\s-1

\s+1\fBShell Widgets\fP\s-1
.sp 2
.nr H1 4
.nr H2 0
.nr H3 0
.nr H4 0
.nr H5 0
.LP
.XS
Chapter 4 \(em Shell Widgets
.XE
.IN "Shell" "" "@DEF@"
.LP
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.
.LP
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.
.LP
The five types of public shells are:
.TS
lw(1.5i) lw(4.25i).
T{
.PN OverrideShell
T}	T{
Used for shell windows that completely bypass the window manager
(for example, pop-up menu shells).
T}
.sp
T{
.PN TransientShell
T}	T{
Used for shell windows that have the
.PN \s-1WM_TRANSIENT_FOR\s+1
property set. The effect of this property is dependent upon the
window manager being used.
T}
.sp
T{
.PN TopLevelShell
T}	T{
Used for normal top-level windows
(for example, any additional top-level widgets an application needs).
T}
.sp
T{
.PN ApplicationShell
T}	T{
Formerly used for the single main top-level window that
the window manager identifies as an application instance and
made obsolete by SessionShell.
T}
.IN "ApplicationShell" "" "@DEF@"
.sp
T{
.PN SessionShell
T}	T{
Used for the single main top-level window that
the window manager identifies as an application instance and
that interacts with the session manager.
T}
.IN "SessionShell" "" "@DEF@"
.TE

.NH 2
Shell Widget Definitions
.XS
\*(SN Shell Widget Definitions
.XE
.LP
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.
.LP
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.
.LP
The eight different types of shells are:
.TS
lw(1.5i) lw(4.5i).
T{
.PN Shell
T}	T{
The base class for shell widgets; provides the
fields needed for all types of shells.
Shell
is a direct subclass of
.PN compositeWidgetClass .
T}
.sp 6p
T{
.PN OverrideShell
T}	T{
A subclass of Shell; used for shell windows that completely
bypass the window manager.
T}
.sp 6p
T{
.PN WMShell
T}	T{
A subclass of Shell; contains fields needed by the
common window manager protocol.
T}
.sp 6p
T{
.PN VendorShell
T}	T{
A subclass of WMShell; contains fields used by
vendor-specific window managers.
T}
.sp 6p
T{
.PN TransientShell
T}	T{
A subclass of VendorShell; used for shell windows that
desire the
.PN \s-1WM_TRANSIENT_FOR\s+1
property.
T}
.sp 6p
T{
.PN TopLevelShell
T}	T{
A subclass of VendorShell; used for normal top-level windows.
T}
.sp 6p
T{
.PN ApplicationShell
T}	T{
A subclass of TopLevelShell; may be used for an application's additional
root windows.
T}
.sp 6p
T{
.PN SessionShell
T}	T{
A subclass of ApplicationShell; used for an application's
main root window.
T}
.TE
.LP
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.

.NH 3
ShellClassPart Definitions
.XS
\*(SN ShellClassPart Definitions
.XE
.LP
Only the
Shell
class has additional class fields, which are all contained in the
.PN ShellClassExtensionRec .
None of the other Shell classes have any additional class fields:
.LP
.KS
.sM
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
        XtPointer extension;
} ShellClassPart, OverrideShellClassPart,
WMShellClassPart, VendorShellClassPart, TransientShellClassPart,
TopLevelShellClassPart, ApplicationShellClassPart, SessionShellClassPart;
.De
.LP
.eM
.KE
The full Shell class record definitions are:
.IN "ShellClassExtension" "" "@DEF@"
.IN "ShellClassExtensionRec" "" "@DEF@"
.LP
.KS
.sM
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct _ShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
} ShellClassRec;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	XtPointer	next_extension;	See Section 1.6.12
	XrmQuark	record_type;	See Section 1.6.12
	long	version;	See Section 1.6.12
	Cardinal	record_size;	See Section 1.6.12
	XtGeometryHandler	root_geometry_manager;	See below
} ShellClassExtensionRec, *ShellClassExtension;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct _OverrideShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	OverrideShellClassPart	override_shell_class;
} OverrideShellClassRec;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct _WMShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
} WMShellClassRec;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct _VendorShellClassRec {
	CoreClassPart	core_class;
	CompositeClassPart	composite_class;
	ShellClassPart	shell_class;
	WMShellClassPart	wm_shell_class;
	VendorShellClassPart	vendor_shell_class;
} VendorShellClassRec;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
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;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
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;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
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;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
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;
.De
.LP
.eM
.KE
.KS
The single occurrences of the class records and pointers for creating
instances of shells are:
.LP
.sM
.Ds 0
.TA .5i 3i
.ta .5i 3i
extern ShellClassRec shellClassRec;
extern OverrideShellClassRec overrideShellClassRec;
extern WMShellClassRec wmShellClassRec;
extern VendorShellClassRec vendorShellClassRec;
extern TransientShellClassRec transientShellClassRec;
extern TopLevelShellClassRec topLevelShellClassRec;
extern ApplicationShellClassRec applicationShellClassRec;
extern SessionShellClassRec sessionShellClassRec;
.sp
extern WidgetClass shellWidgetClass;
extern WidgetClass overrideShellWidgetClass;
extern WidgetClass wmShellWidgetClass;
extern WidgetClass vendorShellWidgetClass;
extern WidgetClass transientShellWidgetClass;
extern WidgetClass topLevelShellWidgetClass;
extern WidgetClass applicationShellWidgetClass;
extern WidgetClass sessionShellWidgetClass;
.De
.LP
.eM
.KE
.KS
The following opaque types and opaque variables are defined
for generic operations on widgets whose class is a subclass of
Shell.
.TS
lw(2.75i) lw(2.75i).
_
.sp 6p
Types	Variables
.sp 6p
_
.sp 6p
T{
.PN ShellWidget
T}	T{
.PN shellWidgetClass
T}
T{
.PN OverrideShellWidget
T}	T{
.PN overrideShellWidgetClass
T}
T{
.PN WMShellWidget
T}	T{
.PN wmShellWidgetClass
T}
T{
.PN VendorShellWidget
T}	T{
.PN vendorShellWidgetClass
T}
T{
.PN TransientShellWidget
T}	T{
.PN transientShellWidgetClass
T}
T{
.PN TopLevelShellWidget
T}	T{
.PN topLevelShellWidgetClass
T}
T{
.PN ApplicationShellWidget
T}	T{
.PN applicationShellWidgetClass
T}
T{
.PN SessionShellWidget
T}	T{
.PN sessionShellWidgetClass
T}
.PN ShellWidgetClass
.PN OverrideShellWidgetClass
.PN WMShellWidgetClass
.PN VendorShellWidgetClass
.PN TransientShellWidgetClass
.PN TopLevelShellWidgetClass
.PN ApplicationShellWidgetClass
.PN SessionShellWidgetClass
.sp 6p
_
.TE
.KE
.LP
The declarations for all Intrinsics-defined shells except
VendorShell appear in
.PN Shell.h
and
.PN ShellP.h .
VendorShell has separate public and private .h files which are included by
.PN Shell.h
and
.PN ShellP.h .
.LP
.PN Shell.h
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.
.LP
The symbolic constant for the
.PN ShellClassExtension
version identifier is
.PN XtShellExtensionVersion
(see Section 1.6.12).
.IN "XtShellExtensionVersion" "" "@DEF@"
.LP
.IN "Shell" "root_geometry_manager"
.IN "root_geometry_manager procedure"
The root_geometry_manager procedure acts as
the parent geometry manager for geometry requests made by shell
widgets.  When a shell widget calls either
.PN XtMakeGeometryRequest
or
.PN XtMakeResizeRequest ,
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
.PN XtGeometryYes ;
if the window manager denies the geometry
request or does not change the window geometry within some timeout
interval (equal to \fIwm_timeout\fP in the case of WMShells), the
.IN "Shell" "wm_timeout" "@DEF@"
.IN "wm_timeout" "" "@DEF@"
root_geometry_manager procedure should return
.PN XtGeometryNo .
If the window manager makes some alternative geometry change, the
root_geometry_manager procedure may return either
.PN XtGeometryNo
and handle the new geometry as a resize or
.PN XtGeometryAlmost
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.
.LP
If no
.PN ShellClassPart
extension record is declared with \fIrecord_type\fP
equal to
.PN \s-1NULLQUARK\s+1 ,
then
.PN XtInheritRootGeometryManager
is assumed.

.NH 3
ShellPart Definition
.XS
\*(SN ShellPart Definition
.XE
.LP
The various shell widgets have the following additional instance
fields defined in
their widget records:
.LP
.IN "ShellPart" "" "@DEF@"
.KS
.sM
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
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;
.De
.KE
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	int	empty;
} OverrideShellPart;
.De
.Ds 0
.TA .5i 1i 1.5i 2.5i
.ta .5i 1i 1.5i 2.5i
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;
.De
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	int	vendor_specific;
} VendorShellPart;
.De
.KE
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	Widget	transient_for;
} TransientShellPart;

typedef struct {
	String	icon_name;
	Boolean	iconic;
	Atom	icon_name_encoding;
} TopLevelShellPart;
.De
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	char *	class;
	XrmClass	xrm_class;
	int	argc;
	char **	argv;
} ApplicationShellPart;
.De
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.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
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;
.De
.LP
.eM
.KE
.KS
The full shell widget instance record definitions are:
.LP
.IN "ShellWidget" "" "@DEF@"
.sM
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
} ShellRec, *ShellWidget;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	OverrideShellPart	override;
} OverrideShellRec, *OverrideShellWidget;
.De
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.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
} WMShellRec, *WMShellWidget;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
} VendorShellRec, *VendorShellWidget;
.De
.KE
.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TransientShellPart	transient;
} TransientShellRec, *TransientShellWidget;
.De
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.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TopLevelShellPart	topLevel;
} TopLevelShellRec, *TopLevelShellWidget;
.De
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.KS
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
.IN "ApplicationShellWidget" "" "@DEF@"
typedef  struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TopLevelShellPart	topLevel;
	ApplicationShellPart	application;
} ApplicationShellRec, *ApplicationShellWidget;
.De
.KE
.KS
.IN "SessionShellWidget" "" "@DEF@"
.Ds 0
.TA .5i 2.5i 4.5i
.ta .5i 2.5i 4.5i
typedef  struct {
	CorePart	core;
	CompositePart	composite;
	ShellPart	shell;
	WMShellPart	wm;
	VendorShellPart	vendor;
	TopLevelShellPart	topLevel;
	ApplicationShellPart	application;
	SessionShellPart	session;
} SessionShellRec, *SessionShellWidget;
.De
.LP
.eM
.KE

.NH 3
Shell Resources
.XS
\fB\*(SN Shell Resources\fP
.XE
.LP
.IN "ShellWidget" "Resources"
The resource names, classes, and representation types specified in
the
.PN shellClassRec
resource list are:
.LP
.TS
lw(1.7i) lw(1.7i) lw(1.2i) .
_
.sp 6p
Name	Class	Representation
.sp 6p
_
.sp 6p
XtNallowShellResize	XtCAllowShellResize	XtRBoolean
XtNcreatePopupChildProc	XtCCreatePopupChildProc	XtRFunction
XtNgeometry	XtCGeometry	XtRString
XtNoverrideRedirect	XtCOverrideRedirect	XtRBoolean
XtNpopdownCallback	XtCCallback	XtRCallback
XtNpopupCallback	XtCCallback	XtRCallback
XtNsaveUnder	XtCSaveUnder	XtRBoolean
XtNvisual	XtCVisual	XtRVisual
.sp 6p
_
.TE
.LP
OverrideShell
declares no additional resources beyond those defined by
Shell.
.LP
The resource names, classes, and representation types specified in
the
.PN wmShellClassRec
.IN "WMShell" "resources"
resource list are:
.LP
.TS
lw(2.1i) lw(2.1i) lw(1.2i) .
_
.sp 6p
Name	Class	Representation
.sp 6p
_
.sp 6p
XtNbaseHeight	XtCBaseHeight	XtRInt
XtNbaseWidth	XtCBaseWidth	XtRInt
XtNclientLeader	XtCClientLeader	XtRWidget
XtNheightInc	XtCHeightInc	XtRInt
XtNiconMask	XtCIconMask	XtRBitmap
XtNiconPixmap	XtCIconPixmap	XtRBitmap
XtNiconWindow	XtCIconWindow	XtRWindow
XtNiconX	XtCIconX	XtRInt
XtNiconY	XtCIconY	XtRInt
XtNinitialState	XtCInitialState	XtRInitialState
XtNinput	XtCInput	XtRBool
XtNmaxAspectX	XtCMaxAspectX	XtRInt
XtNmaxAspectY	XtCMaxAspectY	XtRInt
XtNmaxHeight	XtCMaxHeight	XtRInt
XtNmaxWidth	XtCMaxWidth	XtRInt
XtNminAspectX	XtCMinAspectX	XtRInt
XtNminAspectY	XtCMinAspectY	XtRInt
XtNminHeight	XtCMinHeight	XtRInt
XtNminWidth	XtCMinWidth	XtRInt
XtNtitle	XtCTitle	XtRString
XtNtitleEncoding	XtCTitleEncoding	XtRAtom
XtNtransient	XtCTransient	XtRBoolean
XtNwaitforwm, XtNwaitForWm	XtCWaitforwm, XtCWaitForWm	XtRBoolean
XtNwidthInc	XtCWidthInc	XtRInt
XtNwindowRole	XtCWindowRole	XtRString
XtNwinGravity	XtCWinGravity	XtRGravity
XtNwindowGroup	XtCWindowGroup	XtRWindow
XtNwmTimeout	XtCWmTimeout	XtRInt
XtNurgency	XtCUrgency	XtRBoolean
.sp 6p
_
.TE
.LP
The class resource list for
VendorShell
is implementation-defined.
.LP
The resource names, classes, and representation types that are specified in the
.PN transient\%ShellClassRec
.IN "TransientShell" "resources"
resource list are:
.LP
.TS
lw(1.7i) lw(1.7i) lw(1.2i) .
_
.sp 6p
Name	Class	Representation
.sp 6p
_
.sp 6p
XtNtransientFor	XtCTransientFor	XtRWidget
.sp 6p
_
.TE
.LP
The resource names, classes, and representation types that are specified in the
.PN topLevelShellClassRec
.IN "TopLevelShell" "resources"
resource list are:
.LP
.TS
lw(1.7i) lw(1.7i) lw(1.2i) .
_
.sp 6p
Name	Class	Representation
.sp 6p
_
.sp 6p
XtNiconName	XtCIconName	XtRString
XtNiconNameEncoding	XtCIconNameEncoding	XtRAtom
XtNiconic	XtCIconic	XtRBoolean
.sp 6p
_
.TE
.LP
The resource names, classes, and representation types that are specified in the
.PN application\%ShellClassRec
resource list are:
.LP
.TS
lw(1.7i) lw(1.7i) lw(1.2i) .
_
.sp 6p
Name	Class	Representation
.sp 6p
_
.sp 6p
XtNargc	XtCArgc	XtRInt
XtNargv	XtCArgv	XtRStringArray
.sp 6p
_
.TE
.LP
.KS
The resource names, classes, and representation types that are specified
in the
.PN sessionShellClassRec
resource list are:
.LP
.TS
lw(1.7i) lw(1.7i) lw(1.2i) .
_
.sp 6p
Name	Class	Representation
.sp 6p
_
XtNcancelCallback	XtCCallback	XtRCallback
XtNcloneCommand	XtCCloneCommand	XtRCommandArgArray
XtNconnection	XtCConnection	XtRSmcConn
XtNcurrentDirectory	XtCCurrentDirectory	XtRDirectoryString
XtNdieCallback	XtCCallback	XtRCallback
XtNdiscardCommand	XtCDiscardCommand	XtRCommandArgArray
XtNenvironment	XtCEnvironment	XtREnvironmentArray
XtNerrorCallback	XtCCallback	XtRCallback
XtNinteractCallback	XtCCallback	XtRCallback
XtNjoinSession	XtCJoinSession	XtRBoolean
XtNprogramPath	XtCProgramPath	XtRString
XtNresignCommand	XtCResignCommand	XtRCommandArgArray
XtNrestartCommand	XtCRestartCommand	XtRCommandArgArray
XtNrestartStyle	XtCRestartStyle	XtRRestartStyle
XtNsaveCallback	XtCCallback	XtRCallback
XtNsaveCompleteCallback	XtCCallback	XtRCallback
XtNsessionID	XtCSessionID	XtRString
XtNshutdownCommand	XtCShutdownCommand	XtRCommandArgArray
.sp 6p
_
.TE
.KE
.NH 3
ShellPart Default Values
.XS
\fB\*(SN ShellPart Default Values\fP
.XE
.LP
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:
.TS
lw(1.75i) lw(3i).
_
.sp 6p
Field	Default Value
.sp 6p
_
.sp 6p
geometry	NULL
create_popup_child_proc	NULL
grab_kind	(none)
spring_loaded	(none)
popped_up	T{
.PN False
T}
allow_shell_resize	T{
.PN False
T}
client_specified	(internal)
save_under	T{
.PN True 
for
OverrideShell 
and
TransientShell,
.PN False 
otherwise
T}
override_redirect	T{
.PN True 
for
OverrideShell,
.PN False 
otherwise
T}
popup_callback	NULL
popdown_callback	NULL
visual	T{
.PN CopyFromParent
T}
.sp 6p
_
.TE
.LP
The \fIgeometry\fP field specifies the size and position
and is usually given only on a command line or in a defaults file.
If the \fIgeometry\fP field is non-NULL when
a widget of class WMShell
is realized, the geometry specification is parsed using
.PN XWMGeometry
with a default geometry
string constructed from the values of \fIx\fP, \fIy\fP, \fIwidth\fP,
\fIheight\fP, \fIwidth_inc\fP,
and \fIheight_inc\fP and the size and position flags in the window manager
size hints are set.  If the geometry specifies an x or y position,
then
.PN USPosition
is set.  If the geometry specifies a width or height, then
.PN USSize
is set.  Any fields in the geometry specification
override the corresponding values in the
Core \fIx\fP, \fIy\fP, \fIwidth\fP, and \fIheight\fP fields.
If \fIgeometry\fP is NULL or contains only a partial specification, then the
Core \fIx\fP, \fIy\fP, \fIwidth\fP, and \fIheight\fP fields are used and
.PN PPosition
and
.PN PSize
are set as appropriate.
The geometry string is not copied by any of the \*(xI
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 Section 16.4
in \fI\*(xL\fP.
.LP
The \fIcreate_popup_child_proc\fP procedure is called by the
.PN XtPopup
procedure and may remain NULL.
The \fIgrab_kind\fP, \fIspring_loaded\fP,
and \fIpopped_up\fP fields maintain widget
state information as described under
.PN XtPopup ,
.PN XtMenuPopup ,
.PN XtPopdown ,
and
.PN XtMenuPopdown .
.IN "allowShellResize" "" "@DEF@"
The \fIallow_shell_resize\fP field controls whether the widget contained
by the shell is allowed to try to resize itself.
If allow_shell_resize is 
.PN False , 
any geometry requests made by the child will always return
.PN XtGeometryNo
without interacting with the window manager.
Setting \fIsave_under\fP
.PN True
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 \fIoverride_redirect\fP
.PN True
determines
whether the window manager can intercede when the shell window
is mapped.
For further information on override_redirect,
see Section 3.2 in \fI\*(xL\fP and Sections 4.1.10 and 4.2.2 in the
\fI\*(xC\fP.
The pop-up and pop-down callbacks are called during
.PN XtPopup
and
.PN XtPopdown .
The default value of the \fIvisual\fP resource is the symbolic value
.PN CopyFromParent .
The \*(xI do not need to query the parent's visual type when the
default value is used; if a client using
.PN XtGetValues
to examine the visual type receives the value
.PN CopyFromParent ,
it must then use
.PN XGetWindowAttributes
if it needs the actual visual type.

.LP
The default values for Shell fields in
WMShell
and its subclasses are:
.LP
.IN "XtUnspecifiedShellInt" "" "@DEF@"
.IN "XtUnspecifiedWindow"
.TS
lw(1i) lw(4i).
_
.sp 6p
Field	Default Value
.sp 6p
_
.sp 6p
title	T{
Icon name, if specified, otherwise the application's name
T}
wm_timeout	Five seconds, in units of milliseconds
wait_for_wm	T{
.PN True
T}
transient	T{
.PN True 
for
TransientShell,
.PN False 
otherwise
T}
urgency	T{
.PN False
T}
client_leader	NULL
window_role	NULL
min_width	\fBXtUnspecifiedShellInt\fP
min_height	\fBXtUnspecifiedShellInt\fP
max_width	\fBXtUnspecifiedShellInt\fP
max_height	\fBXtUnspecifiedShellInt\fP
width_inc	\fBXtUnspecifiedShellInt\fP
height_inc	\fBXtUnspecifiedShellInt\fP
min_aspect_x	\fBXtUnspecifiedShellInt\fP
min_aspect_y	\fBXtUnspecifiedShellInt\fP
max_aspect_x	\fBXtUnspecifiedShellInt\fP
max_aspect_y	\fBXtUnspecifiedShellInt\fP
input	T{
.PN False
T}
initial_state	Normal
icon_pixmap	None
icon_window	None
icon_x	\fBXtUnspecifiedShellInt\fP
icon_y	\fBXtUnspecifiedShellInt\fP
icon_mask	None
window_group	\fBXtUnspecifiedWindow\fP
base_width	\fBXtUnspecifiedShellInt\fP
base_height	\fBXtUnspecifiedShellInt\fP
win_gravity	\fBXtUnspecifiedShellInt\fP
title_encoding	See text
.sp 6p
_
.TE
.LP
The \fItitle\fP and
\fItitle_encoding\fP fields are stored in the
.PN \s-1WM_NAME\s+1
property on the shell's window by the WMShell realize procedure.
If the \fItitle_encoding\fP field is
.PN None ,
the \fItitle\fP string is assumed to be in the encoding of the current
locale and the encoding of the
.PN \s-1WM_NAME\s+1
property is set to
.PN XStdICCTextStyle .
If a language procedure has not been set
the default value of \fItitle_encoding\fP is
\fB\s-1XA_STRING\s+1\fP, otherwise the default value is
.PN None .
The \fIwm_timeout\fP 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 \fIwait_for_wm\fP to
.PN False 
(later events may reset this value).
When \fIwait_for_wm\fP is 
.PN False ,
the shell does not wait for a response, but relies on asynchronous 
notification.
If \fItransient\fP is
.PN True ,
the
.PN \s-1WM_TRANSIENT_FOR\s+1
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 \fI\*(xC\fP for more details.
.LP
The realize and set_values procedures of WMShell store the 
.PN \s-1WM_CLIENT_LEADER\s+1
property on the shell window.
When \fIclient_leader\fP 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 \fIclient_leader\fP is NULL and the shell widget has a NULL parent,
the widget's window is used as the value of the
property.
When \fIclient_leader\fP is NULL and the shell widget has a non-NULL parent,
a search is made for the closest shell ancestor
with a non-NULL \fIclient_leader\fP,
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.
.LP
When the value of \fIwindow_role\fP is not NULL, the
realize and set_values procedures store the
.PN \s-1WM_WINDOW_ROLE\s+1
property on the shell's window with the value of the resource.
.LP
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
.PN XtUnspecifiedShellInt ,
the value of the field is modified as follows:
.br
.sp
.TS
lw(2i) lw(3i).
_
.sp 6p
Field	Replacement
.sp 6p
_
.sp 6p
base_width, base_height	0
width_inc, height_inc	1
max_width, max_height	32767
min_width, min_height	1
min_aspect_x, min_aspect_y	-1
max_aspect_x, max_aspect_y	-1
icon_x, icon_y	-1
win_gravity	T{
Value returned by
.PN XWMGeometry
if called,
else \fBNorthWestGravity\fP
T}
.sp 6p
_
.TE

.IN "XWMGeometry"
.LP
If the shell widget has a non-NULL parent, then the
realize and set_values procedures replace the value
.PN XtUnspecifiedWindow
.IN "XtUnspecifiedWindow" "" "@DEF@"
in the \fIwindow_group\fP field with the window id of the root widget
of the widget tree if the
root widget is realized. The symbolic constant
.PN XtUnspecifiedWindowGroup
.IN "XtUnspecifiedWindowGroup" "" "@DEF@"
may be used to indicate that the \fIwindow_group\fP hint flag bit is not
to be set.  If \fItransient\fP is
.PN True ,
the shell's class is not a subclass of
TransientShell,
and \fIwindow_group\fP is not
.PN XtUnspecifiedWindowGroup ,
the WMShell realize and set_values procedures then store the
.PN \s-1WM_TRANSIENT_FOR\s+1
property with the value of \fIwindow_group\fP.
.LP
.KS
Transient
shells have the following additional resource:
.TS
l l.
_
.sp 6p
Field	Default Value
.sp 6p
_
.sp 6p
transient_for	NULL
.sp 6p
_
.TE
.KE
.LP
The realize and set_values procedures of
TransientShell
store the
.PN \s-1WM_TRANSIENT_FOR\s+1
property on the shell window if \fItransient\fP is
.PN True .
If \fItransient_for\fP is non-NULL and the widget specified by
\fItransient_for\fP is realized, then its window is used as the value of the
.PN \s-1WM_TRANSIENT_FOR\s+1
property; otherwise, the value of \fIwindow_group\fP is used.
.LP
.PN TopLevel
shells have the the following additional resources:
.TS
l l.
_
.sp 6p
Field	Default Value
.sp 6p
_
.sp 6p
icon_name	Shell widget's name
iconic	T{
.PN False
T}
icon_name_encoding	See text
.sp 6p
_
.TE
.LP
The \fIicon_name\fP
and \fIicon_name_encoding\fP fields are stored in the
.PN \s-1WM_ICON_NAME\s+1
property on the shell's window by the TopLevelShell realize
procedure.
If the \fIicon_name_encoding\fP field is
.PN None ,
the \fIicon_name\fP string is assumed to be in the encoding of the
current locale and the encoding of the
.PN \s-1WM_ICON_NAME\s+1
property is set to
.PN XStdICCTextStyle .
If a language procedure has not been set,
the default value of \fIicon_name_encoding\fP is
\fB\s-1XA_STRING\s+1\fP, otherwise the default value is
.PN None .
The \fIiconic\fP 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
.PN \s-1WM_CHANGE_STATE\s+1
message (as specified by the \fI\*(xC\fP)
if this resource is changed from
.PN False
to
.PN True
and will call
.PN XtPopup
specifying \fIgrab_kind\fP as
.PN XtGrabNone
if \fIiconic\fP is changed from
.PN True
to
.PN False .
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 \fIinitial_state\fP to
.PN IconicState
if \fIiconic\fP is
.PN True .
.LP
Application
shells have the following additional resources:
.br
.ne 4
.TS
l l.
_
.sp 6p
Field	Default Value
.sp 6p
_
.sp 6p
argc	0
argv	NULL
.sp 6p
_
.TE
.LP
The \fIargc\fP and \fIargv\fP fields are used to initialize
the standard property
.PN \s-1WM_COMMAND\s+1 .
See the \fI\*(xC\fP for more information.
.LP
The default values for the SessionShell instance fields,
which are filled in from the resource lists and by the
initialize procedure, are
.TS
l l.
_
.sp 6p
Field	Default Value
.sp 6p
_
.sp 6p
cancel_callbacks	NULL
clone_command	See text
connection	NULL
current_dir	NULL
die_callbacks	NULL
discard_command	NULL
environment	NULL
error_callbacks	NULL
interact_callbacks	NULL
join_session	T{
.PN True
T}
program_path	See text
resign_command	NULL
restart_command	See text
restart_style	T{
.PN SmRestartIfRunning
T}
save_callbacks	NULL
save_complete_callbacks	NULL
session_id	NULL
shutdown_command	NULL
.sp 6p
_
.TE
.LP
The \fIconnection\fP field contains the session connection object or NULL
if a session connection is not being managed by this widget.
.LP
The \fIsession_id\fP is an identification assigned to the session
participant by the session manager.
The \fIsession_id\fP 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 \fIsession_id\fP field.
When not NULL, the \fIsession_id\fP 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
.PN \s-1SM_CLIENT_ID\s+1
property on the client leader's window.
.LP
If \fIjoin_session\fP is
.PN False ,
the widget will not attempt to establish a
connection to the session manager at shell creation time.
See Sections 4.2.1 and 4.2.4
for more information on the functionality of this resource.
.LP
The \fIrestart_command\fP, \fIclone_command\fP, \fIdiscard_command\fP,
\fIresign_command\fP, \fIshutdown_command\fP, \fIenvironment\fP,
\fIcurrent_dir\fP, \fIprogram_path\fP, and
\fIrestart_style\fP fields contain standard session properties.
.LP
When a session connection is established or newly managed by the shell,
the shell initialize and set_values methods check the values of the
\fIrestart_command\fP, \fIclone_command\fP, and \fIprogram_path\fP
resources.  At that time, if \fIrestart_command\fP is NULL, the value
of the \fIargv\fP resource will be copied to \fIrestart_command\fP.  
Whether or not \fIrestart_command\fP was NULL,
if \*Q\fR-xtsessionID\fP\*U \*Q\fR<session id>\*U does not
already appear in the \fIrestart_command\fP, it will be added by the
initialize and set_values methods at the beginning of the command arguments;
if the \*Q\fR-xtsessionID\fP\*U argument already appears with an incorrect
\fRsession id\fP in the following argument, that argument
will be replaced with the current \fRsession id\fP.
.LP
After this, the shell initialize and set_values procedures check the
\fIclone_command\fP.  If \fIclone_command\fP is NULL, 
\fIrestart_command\fP will be copied to \fIclone_command\fP,
except the \*Q\fR-xtsessionID\fP\*U and following argument will not be copied.
.LP
Finally, the shell initialize and set_values procedures check the
\fIprogram_path\fP.  If \fIprogram_path\fP is NULL, the 
first element of \fIrestart_command\fP is copied to \fIprogram_path\fP.
.LP
The possible values of \fIrestart_style\fP are
.PN SmRestartIfRunning ,
.PN SmRestartAnyway ,
.PN SmRestartImmediately ,
and
.PN SmRestartNever .
A resource converter is registered for this resource; 
for the strings that it recognizes,
see Section 9.6.1.
.LP
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.

.NH 2
Session Participation
.XS
\fB\*(SN Session Participation\fP
.XE
.LP
Applications can participate in a user's session, exchanging messages
with the session manager as described in the \fIX Session Management
Protocol\fP and the \fIX Session Management Library\fP.
.LP
When a widget of
.PN sessionShellWidgetClass
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.

.NH 3
Joining a Session
.XS
\fB\*(SN Joining a Session\fP
.XE
.LP
When a Session shell is created, 
if \fIconnection\fP is NULL,
and if \fIjoin_session\fP is
.PN True ,
and if \fIargv\fP or \fIrestart_command\fP is not NULL,
and if in POSIX environments the 
.PN \s-1SESSION_MANAGER\s+1
environment variable is defined,
the shell will attempt to establish a new connection with the session manager.
.LP
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 \fIconnection\fP 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.
.LP
In the Session shell set_values procedure,
if \fIjoin_session\fP changes from 
.PN False 
to 
.PN True
and \fIconnection\fP is NULL and when in POSIX environments the
.PN \s-1SESSION_MANAGER\s+1
environment variable is defined, 
the shell will attempt to open a connection to the session manager.
If \fIconnection\fP changes from NULL to non-NULL, the
Session shell
will take over management of that session connection and will set
\fIjoin_session\fP to
.PN True .
If \fIjoin_session\fP changes from
.PN False
to
.PN True
and \fIconnection\fP is not NULL, the
Session shell will take over management of the session connection.
.LP
When a successful connection has been established, \fIconnection\fP
contains the session connection ID for the session participant.
When the shell begins to manage the connection, it will call
.PN XtAppAddInput
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 \fIconnection\fP is set to NULL.
.LP
While the connection is being managed, if a 
.PN SaveYourself ,
.PN SaveYourselfPhase2 ,
.PN Interact ,
.PN ShutdownCancelled ,
.PN SaveComplete ,
or
.PN Die
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 
.PN SaveYourselfPhase2Request ,
.PN InteractRequest ,
.PN InteractDone ,
.PN SaveYourselfDone ,
and
.PN ConnectionClosed
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 
.PN SetProperties
or a
.PN DeleteProperties
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.

.NH 3
Saving Application State
.XS
\fB\*(SN Saving Application State\fP
.XE
.LP
The session manager instigates an application checkpoint by sending a
.PN SaveYourself
request.  
Applications are responsible for saving their state in response to the
request.
.LP
When the
.PN SaveYourself
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 \fIcall_data\fP parameter.
.sp
.LP
.KS
The checkpoint token in the \fIcall_data\fP parameter is of type
.PN XtCheckpointToken .
.LP
.IN "XtCheckpointToken" "" "@DEF@"
.IN "XtCheckpointTokenRec" "" "@DEF@"
.sM
.Ds 0
.TA .5i 2i 4i
.ta .5i 2i 4i
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;
.De
.LP
.eM
.KE
The \fIsave_type\fP, \fIinteract_style\fP, \fIshutdown\fP, and \fIfast\fP
fields of the token contain the parameters of the
.PN SaveYourself
message.
The possible values of \fIsave_type\fP are
.PN SmSaveLocal ,
.PN SmSaveGlobal ,
and 
.PN SmSaveBoth ;
these indicate the type of information to be saved.
The possible values of \fIinteract_style\fP are
.PN SmInteractStyleNone ,
.PN SmInteractStyleErrors ,
and
.PN SmInteractStyleAny ;
these indicate whether user interaction would be permitted
and, if so, what kind of interaction.
If \fIshutdown\fP is
.PN True ,
the checkpoint is being performed in preparation for the end of the session.
If \fIfast\fP is
.PN True ,
the client should perform the checkpoint as quickly as possible.
If \fIcancel_shutdown\fP is 
.PN True ,
a 
.PN ShutdownCancelled
message has been received for the current save operation.  (See Section 4.4.4.)
The \fIphase\fP is used by manager clients, such as a window manager,
to distinguish between the first and second phase of a save operation.
The \fIphase\fP will be either 1 or 2.
The remaining fields in the checkpoint token structure are provided for
the application to communicate with the shell.
.LP
Upon entry to the first application save callback procedure, the return
fields in the token have the following initial values:
\fIinteract_dialog_type\fP is 
.PN SmDialogNormal ;
\fIrequest_cancel\fP is
.PN False ;
\fIrequest_next_phase\fP is
.PN False ;
and \fIsave_success\fP is
.PN True .
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.
.LP
The purpose of the token's \fIsave_success\fP field is to 
indicate the outcome of the entire operation to the
session manager and ultimately, to the user.
Returning 
.PN False
indicates some portion of the application state 
could not be successfully saved.  If any token is returned
to the shell with \fIsave_success\fP 
.PN False ,
tokens subsequently received
by the application for the current save operation will show 
\fIsave_success\fP as 
.PN False .
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 \fIsave_success\fP 
.PN False .
.LP
Session participants that manage and save the state of other clients
should structure their save or interact callbacks to
set \fIrequest_next_phase\fP to 
.PN True
when phase is 1, which will cause the shell to send the 
.PN SaveYourselfPhase2Request
when the first phase is complete.  When the 
.PN SaveYourselfPhase2 
message is received, the shell will invoke the save callbacks a
second time with \fIphase\fP equal to 2.
Manager clients should save the state of other clients
when the callbacks are invoked the second time and \fIphase\fP equal to 2.
.LP
The application may request additional tokens while a checkpoint is under way,
and these additional tokens must be returned by an explicit call.
.sp
.LP
.KS
To request an additional token for a save callback response that has a
deferred outcome, use
.PN XtSessionGetToken .
.LP
.IN "XtSessionGetToken" "" "@DEF@"
.sM
.FD 0
XtCheckpointToken XtSessionGetToken(\fIwidget\fP)
.br
      Widget \fIwidget\fP;
.FN
.IP \fIwidget\fP 1i
Specifies the Session shell widget which manages session participation.
.LP
.eM
The 
.PN XtSessionGetToken
function will return NULL if no checkpoint operation is currently under way.
.KE
.sp
.LP
.KS
To indicate the completion of checkpoint processing including user 
interaction, the application must signal the Session shell
by returning all tokens.
(See Sections 4.2.2.2 and 4.2.2.4).
To return a token, use
.PN  XtSessionReturnToken .
.LP
.IN "XtSessionReturnToken" "" "@DEF@"
.sM
.FD 0
void XtSessionReturnToken(\fItoken\fP)
.br
      XtCheckpointToken \fItoken\fP;
.FN
.IP \fItoken\fP 1i
Specifies a token that was received as the \fIcall_data\fP by a procedure
on the interact callback list or a token that was received by a call to
.PN XtSessionGetToken .
.LP
.eM
.KE
.LP
Tokens passed as \fIcall_data\fP to save callbacks are implicitly
returned when the save callback procedure returns.
A save callback procedure should not call 
.PN XtSessionReturnToken 
on the token passed in its \fIcall_data\fP.

.NH 4
Requesting Interaction
.XS
\fB\*(SN Requesting Interaction\fP
.XE
.LP
When the token \fIinteract_style\fP 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 
.PN XtSessionGetToken
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
.PN InteractRequest
to the session manager when an interact request is not already outstanding
for the application.
.LP
The type of interaction dialog that will be requested is specified by
the \fIinteract_dialog_type\fP field in the checkpoint token.
The possible values for \fIinteract_dialog_type\fP are
.PN SmDialogError
and
.PN SmDialogNormal .
If a token is returned with \fIinteract_dialog_type\fP containing
.PN SmDialogError ,
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.  
.LP
When a token is returned with \fIsave_success\fP
.PN False
or \fIinteract_dialog_type\fP
.PN SmDialogError ,
tokens subsequently passed to callbacks during the same active
.PN SaveYourself
response will reflect these changed values, indicating that
an error condition has occurred during the checkpoint.
.LP
The \fIrequest_cancel\fP 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 \fIrequest_cancel\fP field is not examined by the shell.
This is also true of tokens received through a call to 
.PN XtSessionGetToken .

.NH 4
Interacting with the User during a Checkpoint
.XS
\fB\*(SN Interacting with the User during a Checkpoint\fP
.XE
.LP
When the session manager grants the application's request for user interaction,
the Session shell receives an
.PN Interact
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 \fIcall_data\fP.
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
.PN XtSessionReturnToken .
Returning the token completes the current step and triggers the next step
in the sequence.
.LP
During interaction the client may request cancellation of a shutdown.
When a token passed as \fIcall_data\fP to an interact procedure is returned,
if \fIshutdown\fP is 
.PN True
and \fIcancel_shutdown\fP is
.PN False ,
\fIrequest_cancel\fP indicates whether the 
application requests that the pending shutdown be cancelled.
If \fIrequest_cancel\fP is
.PN True ,
the field will also be
.PN True
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
.PN InteractDone
message is sent to the session manager, indicating whether
a pending session shutdown is requested to be cancelled.

.NH 4
Responding to a Shutdown Cancellation
.XS
\fB\*(SN Responding to a Shutdown Cancellation\fP
.XE
.LP
Callbacks registered on the cancel callback list are invoked when the
Session shell processes a
.PN ShutdownCancelled
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
.PN SaveComplete
or a
.PN Die
message.
The \fIcall_data\fP for these callbacks is NULL.
.LP
When the shell notices that a pending shutdown has been cancelled,
the token \fIcancel_shutdown\fP field will be 
.PN True
in tokens subsequently given to the application.
.LP
Receiving notice of a shutdown cancellation does not cancel the 
pending execution of save callbacks or interact callbacks.
After the cancel callbacks execute, if \fIinteract_style\fP is not
.PN SmInteractStyleNone
and the interact list is not empty,
the procedures on the interact callback list will be executed
and passed a token with \fIinteract_style\fP 
.PN SmInteractStyleNone .
The application should not interact with the user, and the Session shell
will not send an 
.PN InteractDone
message.

.NH 4
Completing a Save
.XS
\fB\*(SN Completing a Save\fP
.XE
.LP
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
.PN XtSessionGetToken
have been returned by corresponding calls to
.PN XtSessionReturnToken .
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
.PN XtSessionReturnToken .
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.
.br
.LP
When the application has finished saving state,
the Session shell will report the result to the session manager by
sending the
.PN SaveYourselfDone
message.
If the session is continuing, the shell will receive the
.PN SaveComplete
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 \fIcall_data\fP for these callbacks is NULL.

.NH 3
Responding to a Shutdown
.XS
\fB\*(SN Responding to a Shutdown\fP
.XE
.LP
Callbacks registered on the die callback list are invoked when the
session manager sends a
.PN Die
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 \fIcall_data\fP for these callbacks is NULL.

.NH 3
Resigning from a Session
.XS
\fB\*(SN Resigning from a Session\fP
.XE
.LP
When the Session shell widget is destroyed, the destroy method will
close the connection to the session manager by sending a
.PN ConnectionClosed 
protocol message and will remove the input callback
that was watching for session protocol messages.
.LP
When
.PN XtSetValues
is used to set \fIjoin_session\fP to
.PN False ,
the set_values method of the Session shell will close the
connection to the session manager if one exists by sending a
.PN ConnectionClosed 
message, and \fIconnection\fP will be set to NULL.
.LP
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 \fIjoin_session\fP to
.PN False
before exiting.
.LP
When
.PN XtSetValues 
is used to set \fIconnection\fP to NULL,
the Session shell will stop managing the connection, if one exists.
However, that session connection will not be closed.
.LP
Applications that wish to ensure continuation of a session connection
beyond the destruction of the shell should first retrieve the 
\fIconnection\fP resource value,
then set the \fIconnection\fP resource to NULL, 
and then they may safely destroy the widget without losing control
of the session connection.
.LP
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 \fIconnection\fP to NULL,
remove the input callback, and 
call the procedures registered on the error callback list.
The \fIcall_data\fP for these callbacks is NULL.
.bp