private void EndDrag(bool abort)
            {
                if (abort)
                {
                    return;
                }

                if (!Outline.FloatWindowBounds.IsEmpty)
                {
                    DragSource.FloatAt(Outline.FloatWindowBounds);
                }
                else if (Outline.DockTo is DockPane)
                {
                    DockPane pane = Outline.DockTo as DockPane;
                    DragSource.DockTo(pane, Outline.Dock, Outline.ContentIndex);
                }
                else if (Outline.DockTo is DockPanel)
                {
                    DockPanel panel = Outline.DockTo as DockPanel;
                    panel.UpdateDockWindowZOrder(Outline.Dock, Outline.FlagFullEdge);
                    DragSource.DockTo(panel, Outline.Dock);
                }
            }