In the standard .NET TreeView there is a TreeViewNodeSorter that can be replaced by a custom NodeSorter which derives from IComparer. This allows to sort the tree based upon information in the TreeNodeTag, for instance.

I am using an UltraTree in Outlook style (multicolumn), and I want to sort the tree using the TreeNodeTag. So I am trying to use the UltraTree.Override.SortComparer and the RefreshSort method to trigger, but it does not work...

What should I do ?

You have to assing the IComparer implementation to the column's SortComparer property. You can assing the same instance to multiple columns, assuming the implementation acounts for the different columns that are players in the sort criteria.

Ok, thanks for this advice.

I could you please show me a piece of code of how to set the SortComparer on a column and how to trigger the custom sorting (after the column has been sorted by name for example) using information in the TreeNodeTag of each node ?

For now I have implemented my sorting using the IComparer (on a list this time) by myself with this recursive function :

private void TreeRecursiveSort(UltraTreeNode node)
        {
            List<UltraTreeNode> listOfNodes = new List<UltraTreeNode>();
            foreach (UltraTreeNode childNode in node.Nodes)
                listOfNodes.Add(childNode);

            listOfNodes.Sort(new NodeSorter());

            node.Nodes.Clear();

            foreach (UltraTreeNode childNode in listOfNodes)
                node.Nodes.Add(childNode);

            foreach (UltraTreeNode childNode in node.Nodes)
                TreeRecursiveSort(childNode);
        }

May sounds very simple, but have you tried changing the sort from Default to Ascending, I've just been having a similar problem and that was my issue.

It seems that even if you are not using the sorting, you still need to tell it to do some.