Increments the busy counter for this workbench site. This API should only be used for background work that does not use jobs. As long as there have been more calls to incrementBusy() than to decrementBusy(), the part will show a busy affordance. Each call to incrementBusy must be followed by a call to decrementBusy once the caller no longer needs the part to show the busy affordance.
Note that the job-related methods on this class are another way to let the part show a busy affordance. A part will only appear non-busy if no jobs have been scheduled through this service, and the internal busy counter is not positive.
@since 3.3