public TextBook(string _userid)
 {
     InitializeComponent();
     L1.AppendText(ViewModel.TextBookViewModel.UserText(_userid, 1));
     L2.AppendText(ViewModel.TextBookViewModel.UserText(_userid, 2));
     LK.AppendText(ViewModel.TextBookViewModel.UserText(_userid, 3));
     PractZ.AppendText(ViewModel.TextBookViewModel.UserText(_userid, 4));
     CourcePr.AppendText(ViewModel.TextBookViewModel.UserText(_userid, 5));
     Import.AppendText(ViewModel.TextBookViewModel.UserText(_userid, 6));
     UserId = _userid;
 }