C# 更改ListBoxDragDropTarget中DragDecorator的默认移动

我使用的是Silverlight工具箱中的ListBoxDragDropTarget，我希望在拖动项目时更改项目的移动。因此，在我的列表框面板中，它应该只能在面板内部移动，并且只允许垂直移动，而不允许水平移动

默认情况下，您可以在整个应用程序中从ListBox移动项目，我不认为它应该只能在ListBox中移动

因此，我尝试的是更改弹出控件和DragDecorator控件的RenderTransform，甚至更改模板中画布的RenderTransform

public class FixedListBoxDragDropTarget : ListBoxDragDropTarget
{
    public Popup DragPopupControl { get; set; }
    public DragDecorator DragDecoratorControl { get; set; }

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        DragPopupControl = GetTemplateChild(DragPopupName) as Popup;
        DragDecoratorControl = GetTemplateChild(DragDecoratorName) as DragDecorator;
    }
}

在ListBoxItems上，项目a已附加MouseMove事件

private void TopicUsedControl_MouseMove_1(object sender, System.Windows.Input.MouseEventArgs e)
{
    //Get the Control
    var dragDropPanel = UIHelper.FindChild<FixedListBoxDragDropTarget>(Application.Current.RootVisual, "DragDropControl");

    var transform = dragDropPanel.DragPopupControl.RenderTransform as CompositeTransform;
    var transformDragdecorator = dragDropPanel.DragDecoratorControl.RenderTransform as CompositeTransform;
    if (transform == null && transformDragdecorator == null)
    {
        transform = new CompositeTransform();
        transformDragdecorator = new CompositeTransform();
        dragDropPanel.DragPopupControl.RenderTransform = transform; //PopupControl of Template
        dragDropPanel.DragPopupControl.Child.RenderTransform = transform; //Canvas inside the Template
        dragDropPanel.DragDecoratorControl.RenderTransform = transformDragdecorator; // Dragdecorator of Template
    }

    transform.TranslateX = 0;
    transform.TranslateY = 10;
    transformDragdecorator.TranslateX = 0;
    transformDragdecorator.TranslateY = 10;
}

我尝试将RenderTranform设置为固定值，控件不再移动以测试它。但是它没有发生任何事情，我可以用鼠标移动控件，上面的代码没有任何效果

如何更改或覆盖dragdecorator的默认移动行为