TreeViewColumns allow the user to change the selected node by typing the first letter of a node that is further down the tree. Unfortunately, this feature considers nodes within collapsed portions of the tree, i.e., if a node in a collapsed subtree begins with the letter, the subtree is expanded and the node is selected. That behavior is both counterintuitive and inconsistent with the behavior of Microsoft's file explorer. Navigating a tree by typing the first letter of a node should skip over collapsed subtrees.
You can reproduce the behavior described by using the TreeView replacement demo, as follows: [list]Add two nodes to the root;
Add a node to each of the two root nodes;
Select and collapse the first root node;
Type the letter \"T\".[/list:u]Microsoft's explorer includes an additional useful feature related to keyboard navigation that you should consider. Namely, if you type a letter and there is no node below the current node that begins with the letter, the search starts over at the root of the tree. It beeps if no node begins with the letter.