code: func ExpanderNew(label string) (*Expander, error) {
  	var cstr *C.gchar
  	if label != "" {
  		cstr := C.CString(label)
  		defer C.free(unsafe.Pointer(cstr))
  	}
  	c := C.gtk_expander_new((*C.gchar)(cstr))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapExpander(obj), nil
  }
docs: // ExpanderNew is a wrapper around gtk_expander_new().