static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);
private TimeSpan RetrieveIdleTime()
{
LASTINPUTINFO lastInputInfo = new LASTINPUTINFO();
lastInputInfo.cbSize = (uint)LASTINPUTINFO.SizeOf;
GetLastInputInfo(ref lastInputInfo);
// Diff between current tickCount and tick count at last activity is
// the elapsed idle time.
int elapsedTicks = Environment.TickCount - (int)lastInputInfo.dwTime;
// The "tick count" is the time in milliseconds since the system started.
// So the elapsedTicks is expressed in milliseconds
// Run a system for 24.9 days and you have trouble with this, since
// it'll wrap and be crazy.
// Need to fix this!
if (elapsedTicks > 0) { return new TimeSpan(0, 0, 0, 0, elapsedTicks); }
else { return new TimeSpan(0); }
}