Comment 2 for bug 696138

This is known behavior -- Shotwell only auto-generates Events at import time. If you manually adjust the date/time of a photo later, Shotwell does not move the photo to an event for that date (or create a new one).

Events are kind of a middle ground between a pure chronological hierarchy of your photos and a user-editable set of photo albums. We do want to have a pure chronological view some day: http://trac.yorba.org/ticket/2747 With this feature, your photos would move to a new day if you updated their date/time.

To get the behavior you want, adjust the date/time of the photos, select the photos that comprise a single Event, and choose Events -> New Event. The new event will be sorted by the date of the earliest photo in the group.

Note that you can also drag photos to an existing event to add them to it.