Closing A Messagebox

//In the Form class
private void CloseTheBox(string caption) //Closing a messagebox by caption
{
       IntPtr hWnd = CloseMessageBox.FindWindowByCaption(null, caption);
       if (hWnd != IntPtr.Zero)
           CloseMessageBox.SendMessage(new HandleRef(null, hWnd), CloseMessageBox.CloseNumber, IntPtr.Zero, IntPtr.Zero);
}

//Class containing the members required.
public class CloseMessageBox
{
    [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
    public static extern IntPtr FindWindowByCaption(string lpClassName, string lpWindowName);
    [System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto)]
    public static extern IntPtr SendMessage(HandleRef hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
    const UInt32 WM_CLOSE = 0x0010;
    public static UInt32 CloseNumber
    {
        get
        {
            return WM_CLOSE;
        }
    }
}