The image, and nothing else
The fullscreen media viewer: a shot centred over a deep frosted scrim, with a caption chip and gallery stepping. It rides the same shared overlay machinery as the dialogs, so Escape, the focus trap, the inert page behind, and the counted scroll lock all come for free.
Gallery
Click a shot to open it. The chevrons and the arrow keys step through the set; the consumer owns the collection and the index.