Upon editing image/asset document editor does not switch back to preview mode from edit mode.

STEPS

If you open an image (such as Images . Hippo.jpg) and/or an asset (such as Assets > Hippo.pdf), and then press Edit, you will notice that the Done button is missing next to the Save button. As a consequence, it is not possible to put the open document back into 'preview mode', that is the way it looked when it was first open. See attached missing_done.

But closing the document works, and once reopened shows the expected 'preview mode' state.