SoIdleSensor(3) on Linux
The text 87ebcdc17638, as Debian 8 (Jessie) shipped it.
The SoIdleSensor class is a sensor which will trigger as soon as the application is idle. An SoIdleSensor differs from an SoOneShotSensor in that it will not trigger if the delay queue processing is occurring due to the delay queue timeout, but only when the application is idle.