[santra]

OK, found it. The picture gets saved in the Action's "Note", and Notes can be visible as icons in the Notes column (if said column is enabled). There can also be other text in a Note.

Two shortcuts are available on desktop OF:

"Expand" Action to show Note = Command + " ' "
"Collapse" Action to hide note = Command + " ' " + <Esc>
(The <Esc> is necessary, because when you collapse the Note, OF throws you back into editing of the Action's name.)