Form is a BulletinBoard subclass whose main purpose is to provide constraint-based geometry management for arbitrary children. Form has a number of constraint resources that it uses to place children with respect to the Form, positions within the form, and other children. Most Form-specific behavior is related to this geometry management. Form has no default children of its own. But as a BulletinBoard subclass, Form is an appropriate container for use in dialogs. XmCreateFormDialog creates a Form and a DialogShell parent.
For information on Form's geometry management, see Chapter 14.