This method might be used when a newly-created object has not been assigned a parent. sink() is called internally when the object is assigned a parent. The object is assigned a reference count of 1 at that point, and is kept alive only through its association with the parent.

sink() would be called by a PHP-GTK programmer in a situation where the object needed to be fully referenced, for example after calling ref() and prior to calling unref() on an object, where the object has no reference-giving parent. It's basically a wrapper method that provides access to the GtkObjectFlags value GTK_FLOATING.