public void SignIn(object param)
        {
            if ((NameTextBox != userOldName) && (!HangmanValidators.CanAddUser(NameTextBox, users)))
            {
                MessageBox.Show("This nickname is taken.");
                return;
            }
            if (editMode == true)
            {
                foreach (var user in users.List)
                {
                    if (user.Name == userOldName)
                    {
                        user.Name       = NameTextBox;
                        user.ImageIndex = images.Emojis.IndexOf(ImageSource);
                        break;
                    }
                }
            }
            else
            {
                User user = new User(NameTextBox, images.Emojis.IndexOf(ImageSource));
                user.GameProperty = new Game();
                users.List.Add(user);
            }
            SignInWindow    window   = new SignInWindow();
            SignInViewModel signInVM = new SignInViewModel(users);

            window.DataContext = signInVM;
            App.Current.MainWindow.Close();
            App.Current.MainWindow = window;
            window.Show();
        }
        public void AddUserAndPlay(object param)
        {
            if (!HangmanValidators.CanAddUser(NameTextBox, users))
            {
                MessageBox.Show("This nickname is taken.");
                return;
            }
            int  imageIndex = images.Emojis.IndexOf(ImageSource);
            User user       = new User(NameTextBox, imageIndex);

            user.GameProperty = new Game();
            users.List.Add(new User(NameTextBox, imageIndex));
            serializationActions.SerializeUsers(Constants.UsersFile, users);
            CategoryWindow    categoryWindow = new CategoryWindow();
            CategoryViewModel categoryVM     = new CategoryViewModel(user, true);

            categoryWindow.DataContext = categoryVM;
            App.Current.MainWindow.Close();
            App.Current.MainWindow = categoryWindow;
            categoryWindow.Show();
        }