Call the Calc Opaque Rect method of specified superclass
void PtSuperClassCalcOpaque( PtWidgetClassRef_t *cref, PtWidget_t *widget );
This function calls the Calc Opaque Rect method of the specified superclass. Typically, this function calculates the rectangle representing the portion of the widget that isn't transparent and sets or clears the widget's Pt_OPAQUE flag.
The opaque rectangle for a widget is usually its canvas rectangle or the canvas rectangle derived from its PtBasic-class level.