private void TreeViewMain_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs <object> e)
 {
     if (TreeViewMain != null)
     {
         PrivilegeNode selNode = TreeViewMain.SelectedItem as PrivilegeNode;
         vm.CurPrivilegeNode = selNode;
         vm.GetCurCurPrivilege(selNode);
     }
 }