Mysterious blue cursor

[Chap]

I see this quite often too, it's strange and I would support your theory of placing on surfaces or using decals Kman but actually the other day, I saw it on a section of map I made which didn't have any decals or on surface entites yet. I started wondering whether it's something to do with Alt-Tabbing out of the window (Or some other windows function) that causes a duplicate of a gizmo or something.

That's honestly the best I can come up with xD But if anyone knows the actual reason, I'd love to know haha