func (v *CellLayout) AddAttribute(cell ICellRenderer, attribute string, column int) {
	cstr := C.CString(attribute)
	defer C.free(unsafe.Pointer(cstr))
	C.gtk_cell_layout_add_attribute(v.native(), cell.toCellRenderer(),
		(*C.gchar)(cstr), C.gint(column))
}
func (v *CellLayout) AddAttribute(cell ICellRenderer, attribute string, column int) {
	cstr := C.CString(attribute)
	defer C.free(unsafe.Pointer(cstr))
	C.gtk_cell_layout_add_attribute(v.native(), cell.toCellRenderer(),
		(*C.gchar)(cstr), C.gint(column))
}
// AddAttribute() is a wrapper around gtk_cell_layout_add_attribute().