XtInitializeWidgetClass - Man Page

#include <X11/Intrinsic.h>

void XtInitializeWidgetClass(WidgetClass object_class);

object_class

Specifies the object class to initialize.

If the specified widget class is already initialized, XtInitializeWidgetClass returns immediately.

If the class initialization procedure registers type converters, these type converters are not available until the first object of the class or subclass is created or XtInitializeWidgetClass is called.

X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface