- listen to many events at once (required for vm, very useful to do away with awkward oob pattern most places)

debugging output:
- decorate classes which we expect not to be in the output, warn if we persist them
- 

TRef
    Load
    Unload (save and close reference)
    
    -- we do not want to hold on to references
        -- actually in our case we don't want to save GameWBs at all, we want to persist boards lazily (except for metadata?)