controllerResolver property
Resolver for the controller that shows and hides a Node's label tooltip programmatically. If returns null, the Node's tooltip has no controller.
A JustTooltipController drives one tooltip, and attaching it to a
second fails an assertion. So return a distinct controller per Node, and
the same one for a Node on every call, since this runs on every build:
for example (node) => controllers.putIfAbsent(node.id, JustTooltipController.new).
A label is built only while its row is in view, and a controller drives
it only then; a show() made before the row is built is applied once it
is.
Implementation
final JustTooltipController? Function(Node<T> node)? controllerResolver;