changing the title of a thread

I have discovered, accidentally, a way to change the title of the threads started by me. I remember talking to somebody about it, but I don't remember to whom, so I will post it here hoping they are going to find it.

If you want to change the title of your thread, say on the Ask a Teacher forum, you can go to the page of that forum on which you thread is, and click twice next to the title of your thread (if you click the title, the thread opens of course). The title of your thread should become editable. After editing, press enter.

PS: It only seems to be possible shortly after creating a thread.

I think it's 15 minutes, but am not certain.