@baris Yes. I see also that there is a problem for some other pages like /search ... I will see if I can get it work for all (I thought there were just one place/hook to parse title for all uses but it's not the case).
Sounds like something that should be part of a theme to me.
If you wanted to make such a theme, in-place editing isn't really difficult, you're just swapping visibility between a text block and a text input. Client-side you would only do the swap for the correct user(s), and then server-side verify and actually change the topic title.