I don't know if this is of any use; I didn't know. Took me a while to turn it off!
1. If you link a search panel to your resource, when you click on any word, it searches for it in the search panel, and as an extension, highlights it 'everywhere' in your resource.
2. I'm not sure the value of this in general. Accidentally clicking on 'of' successfully finds all the 'of's' in your library!
3. I can see value, in original languages. Maybe a specialized search panel that automatically searches a clicked-on hebrew or greek word (without needing an Info panel, etc, and linked to analytical lexicons). Or a specialized theology search panel, as an example. Maybe a specialized dictionary for quick translation.
And then, maybe I'm the last to notice this!