did I see a new viewing feature?

[stet]

I don't know if I accidentally tripped a personal option that I can't find now, or if I happened to catch a new feature being tried out yesterday. Anybody else see a thread tree at the top of each discussion's page? The new post(s) would appear in full, and a condensed list of previous responses (poster and first line, I think) was in a scrolling frame above it.

FWIW, I though it was helpful, especially with loading image-heavy threads that I was revisiting.

 

[stet]

never mind -- I just found it, the hybrid viewing mode. But it beats me why it activated and deactivated on its own yesterday.