private string getDroits()
{
    using (MercatorUi._BaseClasses.DroitsStandAlone droits = new MercatorUi._BaseClasses.DroitsStandAlone())
    {
        var group_tech = droits.Tree.Nodes.FirstOrDefault(n => n.Text == "Tech");
        if (group_tech != null)
        {
            var node_guy = group_tech.Nodes.FirstOrDefault(n => n.Text == "Guy");
            if (node_guy != null)
                node_guy.Checked = true;
        }
        var group_comm = droits.Tree.Nodes.FirstOrDefault(n => n.Text == "Comm");
        if (group_comm != null)
        {
            var node_wim = group_comm.Nodes.FirstOrDefault(n => n.Text == "Wim");
            if (node_wim != null)
                node_wim.Checked = true;
        }
        var group_hors = droits.Tree.Nodes.FirstOrDefault(n => n.DataKeyString == "GROUP_??????????");
        if (group_hors != null)
        {
            var node_stephane = group_hors.Nodes.FirstOrDefault(n => n.Text == "Stephane");
            if (node_stephane != null)
                node_stephane.Checked = true;
        }
        return droits.Value;
    }
}