Hello I am thinking about how to change the style of replies to a tree structure. That means the reply to a post will show just below that. like the facebook comments. Is this possible
No, this is not possible.
Discourse is essentially flat and chronological and there is no support for threading apart from one level of direct reply which is a little alike the example in your image. The reply can be viewed directly after the post it replies to but that is in addition to the default position in strict chronological order.
I think that @codinghorror is repeating what he has said elsewhere many times:
There have been a lot of discussions about trees, nesting and threading. Such as this topic:
Which includes specific comments about what you are wanting:
Is it possible to do that by editing the core code?
No, there’s intentionally no capability within Discourse to swap to a threaded model. Topics are linear by design.
You know what I love about Discourse?!
I come searching… thinking I want a feature… and then I read comments from some of the community members and Discourse team, as they answer with a “NO” and go on to explain or reference the “Here’s why…” By the end of reading their references and conclusions I walk away having adopted a new philosophy about the way community should be.
I think there’s always room for constructive debate over a design decision. I’ve seen @tobiaseigen do this all the time, and love the perspective he brings. We usually end in a better place because of debate and having to defend our position. (and others like me can benefit from understanding the rationale for certain decisions.)
Just want to say thanks here to @Remah and @Stephen and so many others for the extra time you take to align new DiscourseFAM members with the philosophical functions and calculated UX design of this great Discourse platform