将Blank SetSystemCursor设置为某个时间跨度

Question

[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern Int32 SystemParametersInfo(UInt32 uiAction,
    UInt32 uiParam, String pvParam, UInt32 fWinIni);

[DllImport("user32.dll")]
static extern bool SetSystemCursor(IntPtr hcur, uint id);

Cursor BlankCursor;
private void CreateBlankCursor()
{
    Bitmap bitmapcursor = new Bitmap(16, 16);
    Graphics g = Graphics.FromImage(bitmapcursor);
    g.FillRectangle(Brushes.Transparent, 0, 0, 16, 16);
    IntPtr ptrCur = bitmapcursor.GetHicon();
    BlankCursor = new Cursor(ptrCur);
}
static public void RevertCursors()
{
    SystemParametersInfo(0x0057, 0, null, 0);
}
private void Form1_Load(object sender, EventArgs e)
{
    //Set Blank cursor here
    System.Threading.Thread.Sleep(3000);            
    RevertCursors();
}

在Form_Load中，我必须将SytemCursor设置为BlankCursor，因为我已经编写了上面的代码，经过一段时间后，它将恢复为默认的箭头光标。