about timers..

If a timer has a period of 100ms and the Action event takes 200ms to complete… What happens? Will the event recurse ?

No. The timer will fire again immediately, though. A timer fires at the next opportunity after the time has expired. Timers are not preemptive. They wait until they get a chance to fire. The period you set in the timer is the minimum time between Action events. The actual time may be more, depending on how busy your app is.