We updated the editor in the Chatter publisher for faster performance and compatibility with Locker Service. But they’re not the only benefits. We improved mentions. When you start to mention someone, the selection list opens right where your cursor is instead of at the bottom of the publisher. And topics gets the same treatment (Yes! Topics in Lightning Experience!). These changes are available in Lightning Experience and Lightning communities.
Here are a few other things to know about the new editor. You can start a numbered list by entering 1. You can start a bullet list by entering a hyphen. When you copy bold text, the bold remains when you paste.