public TimeSpan? GetInactiveTime()
{
LASTINPUTINFO info = new LASTINPUTINFO();
info.cbSize = (uint)Marshal.SizeOf(info);
if (GetLastInputInfo(ref info))
return
TimeSpan.FromMilliseconds(Environment.TickCount - info.dwTime);
else
return null;
}
static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);