SystemClock is more accurate, but cannot call GUI primitives.
You will need to use the SystemClock to get accurate/musical scheduling.
See Clock for general explanation of how clocks operate.
The float you return specifies the delta to resched the function for. Returning nil will stop the task from being rescheduled.
Clear the AppClock's scheduler to stop it.
AppClock.tick is called periodically by the SuperCollider language interpreter. This updates the Scheduler and causes any scheduled tasks to be executed. You should never call this method yourself.