public String setNick(String nickname) {
		if (nickname.length() == 0 || nickname.equals(user.getUsername()))
			return null;
		if (nickname.length() > 20)
			return String.format("Invalid nickname: \"%s\"", nickname);
		nickname = nickname.replaceAll("\\s", "_");
		getUser().setDisplayName(nickname);
		return String.format("Changed nickname to: \"%s\"", nickname);
	}