element to overlay labels onto — normally the canvas's parent, so the overlay and
canvas share a positioning context. The overlay is appended here and absolutely positioned.
scene: Scene
labels are parented to a group added to this scene, so they render and follow the
camera without the caller wiring scene-graph parenting.
element to overlay labels onto — normally the canvas's parent, so the overlay and canvas share a positioning context. The overlay is appended here and absolutely positioned.