private boolean isDifficulty(String cmd) {
        for (GameDifficulty gD : GameDifficulty.values()) {
            if (cmd.equalsIgnoreCase(gD.getName())) {
                if (gD != GameDifficulty.CUSTOM) {
                    Minesweeper.getInstance().getOptionPanel().setDifficulty(gD);
                    Minesweeper.getInstance().restart();
                    return true;
                }
            }
        }
        return false;
    }