private void OnOpenFile()
        {
            var dialog = new OpenFileDialog();
            var result = dialog.ShowDialog();

            if (result == false)
            {
                return;
            }

            _selectedFiles.Add(dialog.FileName);
            ReadFileCmd.RaiseCanExecuteChanged();
        }
 private void OnRemoveFile(string file)
 {
     _selectedFiles.Remove(file);
     ReadFileCmd.RaiseCanExecuteChanged();
 }