[DllImport("urlmon.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern int URLDownloadToFile(
IntPtr pCaller,
[MarshalAs(UnmanagedType.LPWStr)] string szURL,
[MarshalAs(UnmanagedType.LPWStr)] string szFileName,
int dwReserved,
IntPtr lpfnCB
);