public MainWindow()
        {
            //Data initialization:
            DataContext          = this;
            currentFile          = new SoundpackConfiguration();
            generateAllLanguages = false;
            createEmptyLanguagePack();
            string pathToGoogleAuthFile = Environment.GetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS");

            if (pathToGoogleAuthFile == null || pathToGoogleAuthFile == "")
            {
                FirstTimeConfiguration envVarNotSetWindow = new FirstTimeConfiguration();
                this.Hide();
                if (envVarNotSetWindow.ShowDialog() == true)
                {
                    this.Show();
                }
                else
                {
                    this.Close();
                    return;
                }
            }
            try
            {
                client = TextToSpeechClient.Create();
            }
            catch (Exception e)
            {
                MessageBox.Show("Google cloud API could not be initialized. Please make sure it is setup correctly and you have an internet connection.\nFull error message: \n\n" + e.Message);
                Close();
                return;
            }

            //UI initialization:
            InitializeComponent();
            ComboBox_LanguageCode.ItemsSource   = currentFile.LanguagePacks;
            ComboBox_LanguageCode.SelectedIndex = 0;
            DataGrid_FileList.ItemsSource       = ((LanguagePack)ComboBox_LanguageCode.SelectedItem).SystemVoices;
            ComboBox_VoiceName.ItemsSource      = ListVoices(((LanguagePack)ComboBox_LanguageCode.SelectedItem).LanguageCode);
            if (ComboBox_VoiceName.SelectedIndex == -1)
            {
                ComboBox_VoiceName.SelectedIndex = 0;
            }
            GUIRefresh();
        }
        /*******************************************************************************************************************
         * Menu item functions:
         ******************************************************************************************************************/

        //File
        private void MenuItem_New_Click(object sender, RoutedEventArgs e)
        {
            MessageBoxResult result = MessageBox.Show("Do you want to save the current file before creating a new one?", "Save", MessageBoxButton.YesNoCancel, MessageBoxImage.Question);

            switch (result)
            {
            case MessageBoxResult.Yes:
                save(false);
                currentFile = new SoundpackConfiguration();
                createEmptyLanguagePack();
                break;

            case MessageBoxResult.No:
                currentFile = new SoundpackConfiguration();
                createEmptyLanguagePack();
                break;
            }
        }