Facebook is making trails to introduce a new feature to its users, to show when someone is writings comments in Facebook.
Amber Dickso a Twitter user spotted this on her Facebook and shared a screenshot of her Facebook app.
As you can see in the above Screenshot this bubbles appear when someone is typing comment.
COMPUTERERA got confirmation from Facebook that they are testing this chat bubbles for a while. A spokesperson said that we heard from many people that they want to reflect the real time of comments they have on Facebook, so we started testing adding a line above the comment box which shows a friend is typing.