I tried to show the wires experiment to a colleage, he was using firefox and the background and the fadeout/fadein effects didn’t work. I show him the same url in chrome and works fine, but I don’t want to have this problem anymore, so I use prefixfree from Lea Verou and problem solved. The url it’s still the same:

http://www.graph-ic.org/svg-experiments/interact/index.html