private void Ajouter_Click(object sender, RoutedEventArgs e)
{
string nom = Nom.Text;
string prenom = Prenom.Text;
DateTime date = DateTime.Parse(Date_naiss.Text);
string pays = Pays.Text;
string adresse = Adresse.Text;
string mail = Mail.Text;
ClientDAL ajo = new ClientDAL();
ajo.Ajout(nom, prenom, boxContent, date, pays, adresse, mail);
GestionClients page = new GestionClients();
NavigationService.Navigate(page);
}