A gradient given to several objects fits each one's own bounds. With
span: "selection", a linear or radial gradient without its own vector is
placed once on the union of the targets' bounds, at its angle and aspect,
and every target gets that vector in document coordinates, so the ramp
runs on across them. A solid colour, a swatch, a freeform gradient or an
explicit start/end with it is refused before anything changes; the next
object drawn still fits the gradient to itself.
Gert Pellin
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