Just a question here. I haven't used the new Mauku, but I heard that you're using yellow to denote that a tweet is the start of a thread, correct? Like the 3rd image in your first post?

I really don't think that the color is very intuitive to indicate that it's the start of a thread. If I see yellow on a tweet, it makes me immediately think "favorited".

I think it's a lot more intuitive if you simply use tree view style triangles on the right side (not left as in the image below). Triangle pointing to the right to indicate that the tweet is the start of a thread. Upon click, the triangle spins downward exposing the rest of the thread. Having the rest of the thread be slightly indented from the left will further reenforce that those tweets are part of the same thread. Standard tree view behavior that everyone's familiar with.