This might be a feature request, as I think it would be pretty slick.
I find myself moving entire conversations to folders, however, when a new message appears in the conversation, the conversation appears back into my inbox. I would love to be able to select an option that would automatically move any new messages in the previously moved conversation, to that folder. This probably would be a filter that was created behind the scenes, on demand, based on the conversation.
Thanks - keep up the good work!