private void btnMainData_Click(object sender, RoutedEventArgs e)
        {
            wMd = new WindowMainData();

            this.Hide();
            wMd.ShowDialog();
            this.Show();
        }
        private void btnMainData_Click(object sender, RoutedEventArgs e)
        {
            wMd = new WindowMainData();

            this.Hide();
            wMd.ShowDialog();
            this.Show();
        }