The Graph Design dialog lists the designs with a preview of the
selected one and has New Design, Rename, Delete Design, Paste Design
and Select Unused, as the Graph Design dialog of
https://helpx.adobe.com/illustrator/desktop/automate-visualize-data/visualize-data/reuse-graph-designs.html
works; the Marker dialog lists the designs.
graph.design takes them as params:
- new: name or true (the selected art, named "New Design", numbered
when that's taken);
- rename + to: the graphs drawing the design follow it to its new name;
- delete: a name or a list of names;
- paste: as before;
- no params or selectUnused: the designs, and those no graph draws with.
The engine's drawing is unchanged.
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