private void newTree()
        {
            treeView.Nodes.Clear();
            textView.Clear();

            _tree = new TOKTree("");
            TreeNode root = makeTreeNode(_tree.Root);

            treeView.Nodes.Add(root);
            treeView.SelectedNode = root;
        }
        private void openToolStripMenuItem_Click(object sender, EventArgs e)
        {
            OpenFileDialog openDlg = new OpenFileDialog
            {
                CheckPathExists = true,
                Filter          = "Tree Of Knowledge files (*.tok)|*.tok",
                DefaultExt      = "tok",
                FilterIndex     = 1
            };

            if (openDlg.ShowDialog() == DialogResult.OK)
            {
                treeView.Nodes.Clear();
                textView.Clear();

                _tree = new TOKTree("");
                _tree.Open(openDlg.FileName);
                TreeNode root = makeTreeNode(_tree.Root);
                treeView.Nodes.Add(root);
                treeView.SelectedNode = root;
                treeView.ExpandAll();
            }
        }