Plot brush - any chance of enabling Plot tip selections?

[mishatsvelik]

Hi @Fil - I've been playing with the excellent Plot Brush experiment. Is there any chance that it will support pointer click events too? I.e. https://observablehq.com/d/6f3b6e6206c3451b.

[Fil]

Sure we should account for this scenario in #1653; but let's not disperse the discussion.