SandGrid / TreeView - ContextMenu Item?

I don't know whether I'm being an idiot, but I can't figure out how to reference the node in a TreeView on a Right Click (it doesn't select so SelectedElements doesn't work).

Any help much appreciated!

Here's an example of getting the row that was clicked from the MouseUp event.

private void sandGridFolders_MouseUp(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Right)
    {
        GridRow row = sandGridFolders.GetElementAt(sandGridFolders.PointToGrid(new Point(e.X, e.Y))) as GridRow;
        if (row != null)
            MessageBox.Show(row.ToString());
    }
}

Fantastic - thanks very much for that Tim. I'd got as far as the MouseButtons.Right  but couldn't figure out the next bit.

Thanks so much.