Over the years, Twitter has undergone quite a few changes. Some recent ones that come to mind include threading and the upped 280-character limit. The latest changes the company is testing include a new interface for threads, as well as a presence feature that'll show when people are online.
The more noticeable test of the two is the new UI for tweet threads. Each tweet now gets its own bubble, and replies from the original tweeter are given a color fill. While this does make it more clear who's replying to what, it looks like many, myself included, aren't fans of the general look. Some even complained that it makes Twitter look too much like Facebook.
You might also notice some little green dots atop some avatars in the first screenshot, which are status indicators that show whether or not someone is currently on Twitter. This is also something that Facebook implemented first. Should this feature be made official, we can only hope that it can be disabled, like Instagram does with its status indicator dots for DMs.
- Sara Haider (Twitter)