private void editRegisteredPatientsBtn_Click(object sender, RoutedEventArgs e)
 {
     PatientInfo patientToEdit = GetSelectedItem();
     if (patientToEdit != null)
     {
         Patients.RegistrationForBloodWindow AddPatientWindowObj = new Patients.RegistrationForBloodWindow(patientToEdit);
         AddPatientWindowObj.Show();
     }
 }
 private void registrationForBloodBtn_Click(object sender, RoutedEventArgs e)
 {
     Patients.RegistrationForBloodWindow RegistrationForBloodWindowObj = new Patients.RegistrationForBloodWindow(null);
     RegistrationForBloodWindowObj.Show();
 }