GtkDialog::set_response_sensitive

void set_response_sensitive(int response_id, bool setting);

You may use this function to conveniently sensitize/desensitize dialog buttons present in the action_area. This function calls set_sensitive on each widget present in the action_area with the given response ID (passed as a parameter). The setting may either be true or false depending on whether you want the corresponding buttons to be sensitive or not.