Feature summary (what you would like to be able to do and where):
As a user script author I would like to know which entityselector list is active on which textarea on a wikidata entity page.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
Easier to write scripts acting on the entityselector lists

Benefits (why should this be implemented?):