private void draw_grid(dom_model _dom_model, Graphics _gr)
        {
            _gr.DrawRectangles(m_ramka, _dom_model.AllRects);

            for (var _level = 1; _level <= c_levels; ++_level)
            {
                var _lev_rc = _dom_model.Level(_level);
                _gr.DrawLine(Pens.Black, _lev_rc.Location, PointF.Add(_lev_rc.Location, new SizeF(_lev_rc.Width, 0)));
            }
        }