Wpf 如何删除通过样式分配的事件处理程序

我已经创建了一个WPF窗口。我已经为一个文本框创建了样式，其中包含大小信息和一些事件设置器；然后，我创建了一些指定上述样式的文本框

现在，对于一个例子，我需要删除该文本框的事件。但我不能那样做。 即使我做了以下操作，事件也不会分离。它还在那里。 txt9.PreviewLostKeyboardFocus-=txt9_PreviewLostKeyboardFocus

仅当事件附加到样式本身时，才会发生这种情况。 如果它在TextBox控件内，则事件可以很好地分离

我的代码： XAML：

---

您好，我们无法取消在EventSetter中订阅的事件，因为 内部EventSetter类变得不可变，因此 无法修改EventSetter对象。下面是我尝试过的样本 举例说明同样的情况。当我们尝试更改 setterbase类的属性

public partial class MainWindow : Window
{
    KeyboardFocusChangedEventHandler mydelegate, emptydelegate;
    EventSetter eventSetter;

    public MainWindow()
    {
        InitializeComponent();
        emptydelegate  = delegate(object sender, KeyboardFocusChangedEventArgs e)
        {

        };

        mydelegate = delegate(object sender, KeyboardFocusChangedEventArgs e)
        {
            MessageBox.Show("My Own Event is still Unsubscribed");
        };
        eventSetter = new EventSetter();
        eventSetter.Event = TextBox.PreviewLostKeyboardFocusEvent;
        eventSetter.Handler = mydelegate;
        Style myStyle = new System.Windows.Style(txt9.GetType()); 
        myStyle.Setters.Add(eventSetter);
        txt9.Style = myStyle;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        eventSetter.Handler= emptydelegate;
    }
}

---

请尝试删除Windows\u加载事件中的事件。加载窗口时，样式首先应用于文本框。

     public MainWindow()
     {
     txt9.PreviewLostKeyboardFocus -= txt9_PreviewLostKeyboardFocus;
     }

public partial class MainWindow : Window
{
    KeyboardFocusChangedEventHandler mydelegate, emptydelegate;
    EventSetter eventSetter;

    public MainWindow()
    {
        InitializeComponent();
        emptydelegate  = delegate(object sender, KeyboardFocusChangedEventArgs e)
        {

        };

        mydelegate = delegate(object sender, KeyboardFocusChangedEventArgs e)
        {
            MessageBox.Show("My Own Event is still Unsubscribed");
        };
        eventSetter = new EventSetter();
        eventSetter.Event = TextBox.PreviewLostKeyboardFocusEvent;
        eventSetter.Handler = mydelegate;
        Style myStyle = new System.Windows.Style(txt9.GetType()); 
        myStyle.Setters.Add(eventSetter);
        txt9.Style = myStyle;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        eventSetter.Handler= emptydelegate;
    }
}