internal enum FlashMode
{
    FLASHW_CAPTION = 0x1 ,
    FLASHW_TRAY = 0x2 ,
    FLASHW_ALL = FLASHW_CAPTION | FLASHW_TRAY
}

internal struct FlashInfo
{
    public int cdSize;
    public System.IntPtr hwnd;
    public int dwFlags;
    public int uCount;
    public int dwTimeout;

}

[DllImport("user32.dll")]
private static extern int FlashWindowEx(ref FlashInfo pfwi);
private void Flash(System.IntPtr hwnd , FlashMode flashMode , int times)
{
    unsafe
    {
            FlashInfo FlashInf = new FlashInfo();
            FlashInf.cdSize = sizeof(FlashInfo);
            FlashInf.dwFlags = (int)flashMode;
            FlashInf.dwTimeout = 0;
            FlashInf.hwnd = hwnd;
            FlashInf.uCount = times;
            FlashWindowEx(ref FlashInf);
    }
}