Les- If we use an all plastic box for holding a device such as a switch or receptacle the box is not bonded. We must splice all the grounding conductors together and then pigtail for a termination on the device. Multi gang boxes require multiple pigtails or 1 long one that hits all the devices.
We don't use gasketed boxes much but I have seen them. We add a gasket between the trim plate and wall or ceiling, but they are so easy to remove and throw away afterward I consider them worse than useless.
