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();
}