private void treeView_AfterCheck(object sender, TreeViewEventArgs e)
            {
            if (e.Node.Nodes.Count != 0)
                SetSelection (e.Node, e.Node.Checked);
            }

        private void SetSelection(TreeNode node, bool bCheck)
            {
            foreach (TreeNode n in node.Nodes)
                {
                n.Checked = bCheck;
                SetSelection (n, bCheck);
                }
            }