public MainWindow()
        {
            InitializeComponent();
            frmAccueil UCacceuil = new frmAccueil();

            contentControl.Content = UCacceuil;
        }
        private void FermerMed()
        {
            string UC = this.contentControl.Content.ToString();

            if (UC != "frmAccueil")
            {
                frmAccueil UCaccueil = new frmAccueil();
                this.contentControl.Content = UCaccueil;
            }
        }