Art dragged off the canvas and released over the Symbols panel's list
becomes a new symbol (symbol.new with the dragged ids), and a symbol
dragged out of the panel (PanelDrag::Symbol) is placed on the canvas
centred where it is dropped (symbol.place), showing its thumbnail at
the pointer on the way.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>