Arrowhead gains 30 original shapes generated in code, appended after the first
ten so saved names stay stable: Barbed, Half Arrow (left/right), Concave,
Double Arrow, Chevron, Feather, Swallowtail, Reverse Triangle, Triangle to Bar,
Kite, Leaf, Drop, Half Circle, Oval, Target, Tag (+ open), Diamond (open),
Hexagon (+ open), Star, Cross, Plus, Double Bar, Dot on Bar, Slash, Double
Slash, Bracket and Fork. Each is drawn in local units of the head's weight
inside the usual 4 x 4 box, with its own stop for the stroke under it.
Arrowhead::label() names them in the menus. The Stroke panel's arrowhead
dropdowns render every head as the canvas draws it (cached textures, a shared
widgets::doc_preview that the Brushes panel now uses too) in a scrolling list.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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