[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool FlashWindowEx(ref FLASHWINFO pwfi);

[StructLayout(LayoutKind.Sequential)]
public struct FLASHWINFO
{
    public UInt32 cbSize;
    public IntPtr hwnd;
    public UInt32 dwFlags;
    public UInt32 uCount;
    public UInt32 dwTimeout;
}

public const UInt32 FLASHW_ALL = 3;

调用功能：

FLASHWINFO fInfo = new FLASHWINFO();

fInfo.cbSize = Convert.ToUInt32(Marshal.SizeOf(fInfo));
fInfo.hwnd = hWnd;
fInfo.dwFlags = FLASHW_ALL;
fInfo.uCount = UInt32.MaxValue;
fInfo.dwTimeout = 0;

FlashWindowEx(ref fInfo);

这是从Pinvoke.net无端插上