The two controls on top are all you need to get the essential jobs done with this device, a button for switching it on and off (and taking stills) and the sliding record switch -- this set-up also means you can physically feel if it's recording, even when you can't see it.
The dimmer has a unique multi-touch capacitive interface that allows the light to be turned on or off by sliding a finger up or down on the glass switch front.
He knelt down and crawled from the switch rails to the frog of the crossover, sliding his hand along the running surface and the head of the rail and feeling for possible corrugations or dents, or burrs shaved off by the wheels of the locomotives.