protected override void OnEndDrag(bool abort)
            {
                DockPanel.SuspendLayout(true);

                Outline.Close();
                Indicator.Close();

                EndDrag(abort);

                // Queue a request to layout all children controls
                DockPanel.PerformMdiClientLayout();

                DockPanel.ResumeLayout(true, true);

                DragSource.EndDrag();

                DragSource = null;

                // Fire notification
                DockPanel.OnDocumentDragged();
            }