Sometimes I hear someone has a rare wall but someone steals something valuable from it. The mods can not see who did it(due to it being an entity or something) and the culprit gets away. Being able to lock item frames would be nice so people can not steal stuff. In my head, to lock an item frame, you would put a [private] sign on the block the item frame is attached to. The main reason for this addition is to stop thievery from item frames.
Im just saying this because most of the thievery on the server that people get away with is in item frames. The other stuff can be logged and the culprit is usually caught.
There's a setting for it in the /settings. Adding a "lock" on item frames would just 1) complicate things and 2) Where will you place the sign? I mean you can place it in front of it but it'll cover it, that is if you can't place it next to it on a wall. So I will be sticking with no support. Its your responsibility for losing the item in the item frame which sucks but you will need to be more careful regarding who you trust/coop on your island especially when log block can't log item frames unfortunately.
I'm saying if you have too many people trusted, you will never know who took the item. Plus it could allow item frame rotation for locks and stuff like that without people annoyingly stealing the item. I had already said, you place the sign on the block the item frame is attached to. So you could hide the sign on the other side of your rare gallery and nobody would notice.
My bad sometimes my mind skip stuff. But still no support, it would just make more things complicated. As I'm not sure if it's even possible to do so.
It may not have to be a sign, it could be like /lock or something but I see what you mean by complicate things
The main part of this idea came from the fact that they are adding a "fixed" tag in the 1.16 update so this will be much easier to do in that update.
The server is 1.12 so it can't be handled client-side. No support I don't see how this would do much.