private IEnumerable<ICmPossibility> GetSelectedPossibilites(TreeNode node)
{
if (IsNodeSelected(node))
{
ICmPossibility poss = node.Tag as ICmPossibility;
if (poss != null)
yield return poss;
}
foreach (TreeNode childNode in node.Nodes)
foreach (ICmPossibility poss in GetSelectedPossibilites(childNode))
yield return poss;
}