System.Windows.Forms.TreeView._SelectNext C# (CSharp) Méthode

        private void _SelectNext()
        {
            var nextNode = _nodeList.FindIndex(x => x == SelectedNode); // TODO: this is slow implementation. Should remember current selectedIndex.
            while (_SelectNext(nextNode) == false)
            {
                nextNode++;
            }
        }
        private bool _SelectNext(int fromIndex)