Logical layer grouping

[psychogenic]

Having the layers sorted by depth makes sense but offloads lots of the knowledge to the user. Grouping them by "what can actually interact" or by function might be really helpful. We could have basic component topology illustrated through groups, as in this example (please excuse my rough graphics):

[mattvenn]

I like the idea, but I'm not sure how possible it is as so many layers can interact. what might be nice is to be able to turn off un-needed layers as a starting point for lessons. So for the cap lesson you only get the layers you need