This is not true extension request, only idea for minor correction.
If I am not wrong, smart hiding was done for hiding of objects (buildings) around some else objects - to chosen object would be easily demolished or bought or re-built in case of tracks.
But current situation is that when I search for some city building to buy it or demolish it, this tool hide this building too. And I think that it should not be.
So you suggest hiding everything except the building on which tile the cursor is?
Yes. Exactly.
It's a curious and interesting idea, there might have some more good uses of it.
Maybe include an 'invert' option to invert hiden/not-hidden