var s = getDroits();

using (MercatorUi._BaseClasses.DroitsStandAlone droits = new MercatorUi._BaseClasses.DroitsStandAlone())
{
    droits.Value = s;

    var group_tech = droits.Tree.Nodes.FirstOrDefault(n => n.Text == "Tech");
    if (group_tech != null)
    {
        var node_guy2 = group_tech.Nodes.FirstOrDefault(n => n.Text == "Guy2");
        if (node_guy2 != null)
            node_guy2.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 = false;
    }
    s = droits.Value;
}