The save sheet gets "+ Previous page" / "+ Next page" (right to left for
rtl in Page/Book) for a picture that runs over several pages. Moments
store a layout (row | column); pages the selected region does not touch
are dropped. Crops, viewer and gallery draw both layouts.
Dialogs now clean up directly instead of waiting for the "close" event,
which a backgrounded page can deliver late (a closed sheet stayed in the
page and M stopped working).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>