NAME

Constraint − A description of the interface to constraint resources. 

CLASSES

A sub-class of Core and Composite. 

DESCRIPTION

When a constrained composite widget defines constraint resources, all of that widget’s children effectively "inherit" all of those resources as their own.  These constraint resources are set and read just the same as any other resources defined for the child.  This resource "inheritance" extends exactly one generation down, or in other words only the first generation children of a constrained composite widget inherit that (the constrained composite) widget’s constraint resources. 

For example, Panel has three children, a child of class XwstatictextWidgetClass, a child of class XwrowColWidgetClass, and a child of class XwFormWidgetClass.  All of these children inherit all of the constraint resources defined by XwpanelWidgetClass.  None of the children of the rowCol child inherit any of the Panel constraint resources.  None of the children of the Form inherit any of the Panel constraint resources, but all of the children of the Form do inherit all of the constraint resources defined by the XwformWidgetClass. 

Because constraint resources are defined by the "parent" widgets and not the children, the child widgets never directly use the constraint resource data.  Constraint resource data is instead used by the parents to attach child specific data to children. 

SEE ALSO

CORE(3X), XWPANEL(3X)

September 29, 2021