insertLeftItem method

Implementation

@override
void insertLeftItem(IMindMapNode item, int index) {
  if (index >= _leftItems.length) {
    _leftItems.add(item);
  } else {
    _leftItems.insert(index < 0 ? 0 : index, item);
  }
  item.setParentNode(this);
  item.setNodeType(NodeType.left);
  refresh();
  //getMindMap()?.refresh();
  getMindMap()?.onChanged();
}