I found minor bug in INSL behavior. If you create BTRY, surround it with 1px thick INSL, and then add NBLE, NBLE will still became PLSM when it close enough to BTRY. https://powdertoy.co.uk/View.html?ID=11652 Also, maybe there should be single topic for all found bugs?
Well, someone might want battery to give current only in specific direction. I don't really think that someone will mix battery, insulator, and NBLE in one creation, and wouldn't be able to find enough place for just 1px thicker insulator. But it's still bug. If insulator stops battery from giving current to metals, it should stop it for NBLE too.
But what would be the point of using insulator then? We could always use 2px thick glass or diamond or something instead. Again, I am not complaining, I don't even need this to work properly. But it IS a bug. And I understand that you have hell of a work with code cleanup and everything. But every bug must be fixed sooner or later. And you can't fix something if you don't know it exists. So I just want someone to know about this bug so he can add it to fix-in-version-50.2 list.