To handle file lists or objects that don't have specific viewer behaviour. - list the items in the contents panel, showing the label, file type, and thumbnail/keyframe/icon as appropriate - what if there's no label? show the file name instead? - when a download-only item is selected, show it in the viewer area with all its metadata/details and a download link - when a playable/viewable item is selected (e.g. a pdf), it gets its natural viewer behaviour  