private void _contextMenu_Opening(object sender, CancelEventArgs e)
{
// Find the node we're on
Point pt = _treeCtrl.PointToClient(TreeView.MousePosition);
BindingTreeNode node = (BindingTreeNode)_treeCtrl.GetNodeAt(pt.X, pt.Y);
_treeCtrl.SelectedNode = node;
if (node == null)
EventsHelper.Fire(_selectionChanged, this, EventArgs.Empty);
e.Cancel = !CollectionUtils.Contains<ToolStripItem>(_contextMenu.Items, item => item.Available);
}