parentNode.add(ret);
// Tell the model that a new node has been inserted
DefaultTreeModel model = (DefaultTreeModel)cellHierarchyTree.getModel();
int childIndex = parentNode.getIndex(ret);
model.nodesWereInserted(parentNode, new int[] { childIndex });
// Recursively iterate through all of the Cell's children and add to
// the tree.
List<Cell> children = cell.getChildren();
for (Cell child : children) {