MainWindow_TNG parent = (MainWindow_TNG)Application.Current.Windows[1]; // because the (hidden) licence window is alway index 0

        public Page_Input()
        {
            parent.currentPage = OpenPseudonymiser.MainWindow_TNG.Page.ChooseSource;
            parent.SetPageHeader(parent.currentPage);
            InitializeComponent();
            parent.DisableBack();
            parent.DisableNext();
            parent.DisableFinish();
            ValidatePage();
        }
 public void LockUIElementsForProcessing(bool locked)
 {
     if (locked)
     {
         parent.DisableBack();
         parent.DisableFinish();
         parent.DisableHelp();
     }
     else
     {
         parent.EnableBack();
         parent.EnableFinish();
         parent.EnableHelp();
     }
     btnCancel.IsEnabled       = locked;
     btnSelectOutput.IsEnabled = !locked;
 }