This request arouse out of a discussion at a workshop. In my drawing, I saw modifications of the same query as branches, while completely new queries formed new top-level nodes. Of course it is difficult to figure out what creates a new query and what is a derivative query, so this may not be possible to do accurately when there is no explicit branching (explicit branching = giving the query a new name?).
It would still be helpful to simply be able to browse through my previous queries and rapidly switch between them. I can imagine that I might want to build up a query by checking two tables and then joining them, or I might be building up a new query and forgotten an earlier result that I want to build on.