public void Drawings1OnWorkCompleted(object sender, WorkCompletedEventArgs e)
        {
            ViewBuilder vb = e.WorkUnit as ViewBuilder;

            if (vb != null)
            {
                vb.AddToDrawings(drawings1);

                if (drawings1.GetActiveSheet() == null)
                {
                    drawingsPanel1.ActivateSheet(drawings1.Sheets[0].Name);

                    if (_treeIsDirty)
                    {
                        drawingsPanel1.SyncTree();
                        _treeIsDirty = false;
                    }

                    drawings1.ZoomFit();
                }
            }

            EnableUIElements(true);
        }