c#WPF无法获取父窗口

ChildWindow childWindow = new ChildWindow();
childWindow.Owner = this;
childWindow.ShowDialog();

Window parentWindow = this.Owner;

// 在子窗口中定义事件
public event EventHandler<ParentWindowEventArgs> ParentWindowEvent;

// 在子窗口中触发事件
if (ParentWindowEvent != null)
{
    ParentWindowEvent(this, new ParentWindowEventArgs(this.Owner));
}

// 在父窗口中注册事件
childWindow.ParentWindowEvent += new EventHandler<ParentWindowEventArgs>(ChildWindow_ParentWindowEvent);

// 在父窗口中实现事件处理程序
private void ChildWindow_ParentWindowEvent(object sender, ParentWindowEventArgs e)
{
    Window parentWindow = e.ParentWindow;
    // 在这里可以获取父窗口的实例，并进行通信操作
}