Quickview read timer?

Is there a setting (probably a registry hack) that times how long a message is displayed in the quickviewer before it is flagged as "read"? I have a user who jumps around in her inbox to pick messages to work on, and if she moves or deletes a message, the next message in her inbox gets previewed and flagged as Read, but she wants to keep it Unread so she can go back to it later. I may be thinking of an Outlook setting, but I remember there being a time delay option for a previewed message before the status is changed. For now, she is manually changing the status back to Unread.