Methods, systems and apparatus, including computer program products, for
user interfaces. A user interface uses metadata of digital objects to
navigate through a data structure that includes multiple containers to
organize digital objects, such as digital images. Based on the metadata,
the user interface can ignore empty containers that have no associated
digital objects. The data structure can be presented without the empty
containers, or the empty containers can be presented but automatically
skipped when a user navigates through the data structure. For example in
a calendar view, in which each day represents a container for images,
days without images are automatically skipped when the user navigates in
the calendar view.