Fix duplicate ids

This prevents having multiple elements having the same ids between plots. However, I'm not really sure if this prevents duplicate ids within the same plot.

This fixes the width issue we saw in firefox. The reason we saw it was obvious in firefox is that firefox is pretty strict regarding w3 standards (ie: *forbidden* to have multiple elements with the same id in an html document). Since Chrome is very loose in that regard (which is *bad* imo), it did not react the same way.