I didn't know about that. That's super-useful, thanks for the tip!
But my problem is a little bit different; I have some sprites that get duplicated when they shouldn't be on new layouts. It's all a bit weird and seems to have started happening out of the blue. It's probably something I've done *somewhere* that I forgot about but I can't do a search for these sprites except by going through each event sheet one by one.
So I'm thinking a more comprehensive search function would help make debugging a lot easier, at least for larger projects.