Cursor Focus in Chatter Publisher Has Changed
We changed the cursor focus when you click in the Chatter publisher to post something. Old way: Focus goes to the To field. New way: Focus snaps your cursor to the text box. It saves you the step of positioning your cursor, so you can start posting right away.
Where: This change applies to Lightning Experience in Contact Manager, Developer, Enterprise, Essentials, Group, Performance, Professional, and Unlimited editions.