private void AddGroup(Group group)
 {
     var dialog = new AddGroupDialog();
     if (dialog.ShowDialog() != true)
         return;
     var viewModel = dialog.DataContext as AddGroupDialogViewModel;
     if (viewModel == null)
         return;
     MachineCompositHandler.WriteComposit(viewModel.GroupName, group?.Name);
     OnPropertyChanged(nameof(Groups));
 }
 private void SelectedItemChanged(Group group)
 {
     SelectedGroup = group;
 }