Select API
Core RectSelectController configuration, callbacks, and geometry binding.
RectSelectController implements background rectangle selection. Construct
it with new RectSelectController(engine, parent, { callbacks }).
SelectCallbacks receives selection start and change events; a SelectChangeEvent carries the selected nodes for the in-progress marquee.
Bind a marquee element with bindGeometryWriter(callback): the callback
receives a SelectRect (x, y, width, height, visible) and writes
element geometry directly, returning a cleanup function. Destroy the
controller with destroy(false) when tearing down.
Read the settled selection with getSelectedNodes(engine). Per-node
selection behavior (replace, toggle, append) is decided by each node’s resolveSelectionMode callback.