How does "Limit Search to selected item in Data Explorer panel" work?

[MrAnalogy]

When I add a query to my Search window (linking to the original query, I guess) the "search only siblings" seems to become "Limit Search to selected item in Data Explorer panel".

I'd like to be able to search BranchX clicking the same place everytime, rather than having to navigate to s branch and click it.

SCENARIO:
I want to search my GTD "Next Actions" without having to navigate to \Active \ Active Next Actions.

I saw somewhere someone mentioned creating a Query and then "Linking the Contacts directory to it".

Maybe that would help?