Since SLS lets you control lights, I've built up several script systems and a trigger based around lighting that uses SLS functionality. First, I've added the ability to turn lights on/off by doing appropriate damage to the light source. Normally this is fire for on, and ice for off, but "cold lights" would just be a matter of a quick script edit. You can also turn lights on/off via a number of non-damaging spells. Gust of Wind or Darkness etc will turn off a torch for instance. Magical lights are not able to be turned off via gust of wind, but can be dispelled. A variable on the light records the level of the creature that enchanted the light, and the dispel line of spells are very straightforward to implement. And of course some light sources can simply be used to turn them on/off.
So what? Well this is where my trigger comes in. I have a trigger for the lightsphere of a lightsource. The trigger reduces the hide skill of pc's that enter (not npc's as the ai can't deal with that, a sneaky npc doesn't stick to shadows), and restores it on exiting the trigger. But the trigger is also aware of the status of the light, if the light is off, the pc gets no bonus entering the trigger. The scripts that allow turning on and off lights also are aware of the trigger assigned to them, and adjust the hide skill accordingly, so for instance if the player is in the trigger when the light goes on, the hide bonus is immediately removed. This is demonstrated in this trigger awareness video .
Finally, the trigger looks for a local variable named guards_lights on anything that enters, and keeps track of if a guard can use the light source (a variable on the light source). Npc's with the guards_lights variable will move to a light source and turn the light back on if it's off and they can use it. Your average castle guard can light a torch, but not turn on a magical light.
In this youtube video you can see the guarded light function in action. link The pc hits the torch with an ice arrow at the very beginning of the video. You can see the guard enter the trigger (marked by the mushrooms for the demo). As he enters the trigger he notices the light is out, has a speakstring that plays "darn light!", moves to the lightsource, plays a use animation (it should loop until the light turns on but doesn't in this demo video), the light comes back on, and he then continues on his patrol path.