Here, let me demo it via a short video:
MalwareTips app _Chrome 05-01-2017.mp4
I stop my cursor on the 'Alert' icon that has a red unread indicator. Then, I donot move the cursor, but the red indicator goes off (when the alerts are displayed) and the width of the 'Alert' icon decreases, the 'Alert' icon and the 'Messages' icon shift a bit to the right.
So, now, the cursor being stable where it was, the 'Messages' icon comes beneath the cursor. Hence the messages panel opens up as shown in the video.