You might need to mark a ticket as "unread" even after you have viewed it because it might need a second look or you're still not done resolving the query.
Here's how you can do it:
1) Select the ticket.
2) In the ticket header, look at the icons on the right side of the second row. Click the icon named "Mark as Unread" (hover over an icon to see its name).
3) Once you do, the ticket is "unread" and you can get back to it later.
