C # directx video player problems.

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            panel1.Dock = DockStyle.Fill;
        }

        private void panel1_DoubleClick(object sender, EventArgs e)
        {
            if (this.WindowState != FormWindowState.Maximized)
            {
                this.WindowState = FormWindowState.Maximized;
                this.FormBorderStyle = FormBorderStyle.None;
            }
            else
            {
                this.WindowState = FormWindowState.Normal;
                this.FormBorderStyle = FormBorderStyle.Fixed3D;
            }
        }
    }