private void AssociatedObject_Loaded(object sender, RoutedEventArgs e) { if (!(sender is Panel panel)) { return; } if (panel.Background == null) { panel.Background = Brushes.Transparent; } panel.AllowDrop = true; panel.DragEnter += new DragEventHandler(AssociateObject_DragEnter); panel.DragOver += new DragEventHandler(AssociatedObject_DragOver); DragManager.RegisterDragContext(panel, AssociatedObject_DropCompleted); }