Currently, the set slot block works on multi-variable slots - kind of.
When setting the slot to be a list of values:
set slot [multi-upvar slot V] to (list [foo] [bar] [baz] [quux] @<>) sets the slot to ((\ )) ((\ )) ((\ )) ((\ )) @<:> rather than ((foo)) ((bar)) ((baz)) ((quux )) @<:> . Would it be possible to have the slots be allowed to use the latter behavior?
Where does that “set slot … to …” block come from? You can do this:
They’re talking about in the context of a custom block, similar to this.
When you click on “expand”, it results in this.
And the set slot block comes from the block palette
Another note is that this variables slot is not the special variables slot, it’s an actual variadic upvar slot that I could only create with metaprogramming. The slot does not show up in the set slot menu if it’s the special variables slot.
or, what I did, using group slot 12 – something that snap libraries have used 
Aha, thanks! Now I understand. No, supporting that is definitely nowhere on my list for the foreseeable future 
