Specifications

Athena Widget Set libXaw 1.0.7

app_con_return Returns the application context of this application, if non-NULL.

application_class Speciﬁes the class name of this application, which is usually the generic

name for all instances of this application. Auseful convention is to form

the class name by capitalizing the ﬁrst letter of the application name. For

example, the application named ‘‘xman’’has a class name of ‘‘Xman’’.

options Speciﬁes howtoparse the command line for anyapplication-speciﬁc

resources. The options argument is passed as a parameter to XrmPar-

seCommand.For further information, see Xlib — C Language X Inter-

face.

num_options Speciﬁes the number of entries in the options list.

argc_in_out Speciﬁes a pointer to the number of command line parameters.

argv_in_out Speciﬁes the command line parameters.

fallback_resources Speciﬁes resource values to be used if the site-wide application class

defaults ﬁle cannot be opened, or NULL.

args Speciﬁes the argument list to use when creating the Application shell.

num_args Speciﬁes the number of arguments in args.

This function will remove the command line arguments that the toolkit reads from argc_in_out,

and argv_in_out.Itwill then attempt to open the display.Ifthe display cannot be opened, an

error message is issued and XtAppInitialize terminates the application. Once the display is

opened, all resources are read from the locations speciﬁed by the Intrinsics. This function returns

an ApplicationShell widget to be used as the root of the application’swidget tree.

2.3. Creating a Widget

Creating a widget is a three-step process. First, the widget instance is allocated, and various

instance-speciﬁc attributes are set by using XtCreateWidget.Second, the widget’sparent is

informed of the newchild by using XtManageChild.Finally,Xwindows are created for the par-

ent and all its children by using XtRealizeWidget and specifying the top-most widget. The ﬁrst

twosteps can be combined by using XtCreateManagedWidget.Inaddition, XtRealizeWidget

is automatically called when the child becomes managed if the parent is already realized.

To allocate, initialize, and manage a widget, use XtCreateManagedWidget.

Widget XtCreateManagedWidget(name, widget_class, parent, args, num_args)

String name;

WidgetClass widget_class;

Widget parent;

ArgList args;

Cardinal num_args;

name Speciﬁes the instance name for the created widget that is used for retrieving wid-

get resources.

widget_class Speciﬁes the widget class pointer for the created widget.

parent Speciﬁes the parent widget ID.

args Speciﬁes the argument list. The argument list is a variable-length list composed

of name and value pairs that contain information pertaining to the speciﬁc widget

instance being created. Forfurther information, see Section 2.7.2.

num_args Speciﬁes the number of arguments in the argument list. If the num_args is zero,

the argument list is neverreferenced.

When a widget instance is successfully created, the widget identiﬁer is returned to the application.

If an error is encountered, the XtError routine is invokedtoinform the user of the error.