@Override
	public void remove() {
		GTreeNode parent = lastNode.getParent();
		if (parent == null) {
			throw new IllegalArgumentException("Can't delete root node!");
		}
		parent.removeNode(lastNode);
		nodeQueue.removeAll(lastNode.getChildren());
	}
Implements an iterator over all GTreeNodes in some gTree (or subtree).  The nodes are
return in breadth first order.
Ghidra/Framework/Docking/src/main/java/docking/widgets/tree/support/BreadthFirstIterator.java