private void btnExporter_Click(object sender, RoutedEventArgs e)
        {
            //TODO: exporter les exercices sélectionnées en incluant leur fichier xml, wav et txt, avec le xml les énumérant et le toute dans un zip.
            string targetDirectory  = "";
            string dateExported     = DateTime.Now.ToString("yyyyMMddHHmmss");
            string zipfolder        = TEMP_PATH + "\\" + dateExported;
            CommonOpenFileDialog fd = new CommonOpenFileDialog();

            fd.Title            = "Exporter une série d'exercices";
            fd.IsFolderPicker   = true;
            fd.InitialDirectory = EXERCICES_FOLDER;

            if (fd.ShowDialog() == CommonFileDialogResult.Ok)
            {
                targetDirectory = fd.FileName;

                Directory.CreateDirectory(targetDirectory);
                Directory.CreateDirectory(zipfolder);

                var activitiesConfig = new XmlHelper(false);
                var root             = activitiesConfig.AddToRoot("Activities", string.Empty);
                activitiesConfig.AppendToNode(root, "Date", dateExported);
                foreach (var activity in activityListInstance.SelectedActivityList)
                {
                    activitiesConfig.ImportNode(root, XmlHelper.MakeActivityNode(activity));
                }
                activitiesConfig.Save(zipfolder + "\\config.xml");

                foreach (ExerciceVM selectedFile in ListSelected.Items)
                {
                    File.Copy(EXERCICES_FOLDER + "\\" + selectedFile.Example_wav_path, zipfolder + "\\" + selectedFile.Example_wav_path);
                }

                ZipFile.CreateFromDirectory(zipfolder, targetDirectory + "\\" + txtConfigName.Text + ".zip");
            }
        }