Candidate(DropController dropController) {
this.dropController = dropController;
Widget target = dropController.getDropTarget();
if (!target.isAttached()) {
throw new IllegalStateException(
"Unattached drop target. You must call DragController#unregisterDropController for all drop targets not attached to the DOM.");
}
targetArea = new WidgetArea(target, null);
}
Widget getDropTarget() {
return dropController.getDropTarget();
}