Change titles of threads in 'for sale'?

[schnee]

I PM'd a mod about this but haven't heard back.

I wanted to change the title of one of my threads in the 'for sale' area.
Advanced Editing doesn't seem to do it, even though it looks like it should.

Is this a bug, or a decision?

If it's a decision, why? I'd love to put 'price drop' in the title to let people know of a change without starting a new thread.

Thanks in advance.