Fill and stroke layers (and type characters' fill and stroke) carry an
overprint flag. object.setOverprint {fill?, stroke?, item?, ids?} sets it
(groups: their contents; type: its characters too; one undo step, none when
nothing changes) and attributes.info reads it back (null where mixed).
Overprint Preview and Separations Preview draw overprinting fills and strokes
with Multiply. The old Document.unknown["overprintBlack"] id list migrates to
the new flags on load; Overprint Black now sets the flags.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
While a mask is edited, the Transparency panel and its commands act on the
masked object (Release leaves editing first). Mask commands and
transparency.set take ids and work without a selection; Make Opacity Mask
with one object adds an empty mask and enters editing. Opacity is 0..100 in
every command. transparency.info reports the panel's values with null for
mixed ones, shown blank. Saves and exports never include the editing layer
(Document::without_edit_modes; mask_edit is not serialized).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>