public FrmMainWindow()
        {
            InitializeComponent();
            FrmLogIn     loginForm = new FrmLogIn();
            DialogResult res       = loginForm.ShowDialog();

            if (res == DialogResult.OK)
            {
                MessageBox.Show("Enabled!!");
            }
            else
            {
                this.Close(); //The main application is closed, when the user
                              //does not enter the right password but instead
                              //presses cancel! A different action does not make
                              //sense.
            }

            //Testzwecke:
            this.customers = new List <Customer>();
            for (int i = 0; i < 10; i++)
            {
                this.customers.Add(new Customer(((char)(i + 'A')).ToString()));
            }
            this.WriteCustomerDB();
            //End Testzwecke!
        }
        /// <summary>
        /// Loads the Login-Form and enables the Main-Form if the password is correct.
        /// Otherwise it closes the Form.
        /// </summary>
        /// <param name="sender">Form that is loaded</param>
        /// <param name="e">Form loaded event</param>
        private void FrmMainWindow_Load(object sender, EventArgs e)
        {
            //Fürs Testen kann die Passwortabfrage auskommentiert werden!!
            //this.InitializeForm();
            FrmLogIn     loginForm = new FrmLogIn();
            DialogResult res       = loginForm.ShowDialog();

            if (res == DialogResult.OK)
            {
                MessageBox.Show("Enabled!!");
                this.InitializeForm();
            }
            else
            {
                this.Close(); //The main application is closed, when the user
                //does not enter the right password but instead
                //presses cancel! A different action does not make
                //sense.
            }
        }