code: func (po *PrintOperation) Run(action PrintOperationAction, parent *Window) (PrintOperationResult, error) {
  	var err *C.GError = nil
  	c := C.gtk_print_operation_run(po.native(), C.GtkPrintOperationAction(action), parent.native(), &err)
  	res := PrintOperationResult(c)
  	if res == PRINT_OPERATION_RESULT_ERROR {
  		defer C.g_error_free(err)
  		return res, errors.New(C.GoString((*C.char)(err.message)))
  	}
  	return res, nil
  }
docs: // Run() is a wrapper around gtk_print_operation_run().