Returns the number of ticks since last user activity (i.e. KYBD/Mouse)
_Timer_GetIdleTime ( )
|Success:||integer ticks since last (approx. milliseconds) since last activity|
|Failure:||Sets @extended = 1 if rollover occurs (see remarks)|
The current ticks since last system restart will roll over to 0 every 50 days or so, which makes it possible for last user activity to be before the rollover, but run time of this function to be after the rollover.
If this happens, @extended = 1 and the returned value is ticks since rollover occured.