Dropdown:Using Dropdowns that interact with eachother's queries

Build 790 on feat/dropdown-overhaul
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Baseline History
Build 790abf0aaa
Current build. There are unaccepted changes, so build 32 is still the baseline.
Build 294a94e89
Accepted by Adam.
Build 2817e67c7
Accepted by Adam.
Build 26e9ac958
Accepted by Adam.
Commenting is disabled because there's a newer build on this branch