Over at hamang.net -

"Shortly explained, the idea is that when the build breaks, the red lamp is turned on and when the build is ok, the green lamp is turned on. It's a pretty cool feature, so I thought of moving this idea a step further! Lamps are for dinosaurs :)"

http://www.hamang.net/index.php?option=com_content&task=view&id=16&Itemid=9