void ultraGrid_MouseClick(object sender, MouseEventArgs e)
{
    if ( e.Button == MouseButtons.Right )
    {
        UltraGrid control = sender as UltraGrid;
        UIElement controlElement = control.DisplayLayout.UIElement;
        UIElement elementAtPoint = controlElement != null ? controlElement.ElementFromPoint( e.Location ) : null;
        UltraGridRow row = elementAtPoint != null ? elementAtPoint.GetContext( typeof(UltraGridRow) ) as UltraGridRow : null;
        int index = row != null ? row.Index : -1;
    }
}