It should be obvious. Put Elvis in the building. Take him out again. I realised you could put code into the backgrounds but it seems that the code's scope is universal for every background if you do that. Only in the sprites does the code have a more local 'scope'. Hmmm.
I played around with a few If then statements and some operators until I got Elvis to do what I wanted him to...! I think I made some sort of elementary slider feature using the Broadcast feature for the disco lights- not sure how though. Move the pointer from left to right to see the effect.
