Can't add topic pic when editing an existing thread.

I know it's kinda trivial, and not sure if anyone else bothered to point this out before, but I wanted to bring it to attention that once you make a thread, you can't add or change the topic picture of the thread.

I kinda wanted to add a topic picture in a thread I made, because I couldn't figure out what to put when I was actually making the thread itself.

I find that a bit annoying. Is it intention or some kinda mistake? If it's a mistake, I hope it's fixed, because fixing something like this probably doesn't take *that* long.

It's been bothering me for a while.

Also, editing a thread with a topic pic makes the pic disappear.