private void textBox1_TextChanged(object sender, EventArgs e)
        {
            TextChanged();
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            TextChanged();
        }

        private void TextChanged()
        {
            if (textBox1.Text.Length > 0 && textBox2.Text.Length > 0)
            {
                button1.Enabled = true;
            }
            else
            {
                button1.Enabled = false;
            }
        }