Clicking an attached image routed it through normalizeOrLocalPreviewTarget and
into the right rail, where it rendered as a small contained <img> inside a
pane built for reading and editing files. The bytes were already in hand as a
data URL, so the rail's whole read/edit/reload apparatus was doing nothing for
a picture the user just wanted to look at.
Route images with a resolved thumbnail to ImageLightbox — the same overlay the
thread uses — so the attachment previews at full size with the download action,
and drop the dataUrl/previewKind graft that only existed to make the rail
render bytes it shouldn't have been handed. Non-image attachments, and images
whose thumbnail never resolved, still fall through to the rail unchanged.
Brooklyn Nicholson
d8cb73b4ab