如何在WPF RichTextBox中设置选项卡大小

<RichTextBox x:Name="MyRichTextBox">
    <FlowDocument>
        <Paragraph>
            <Run>这是一个测试文本。</Run>
        </Paragraph>
    </FlowDocument>
</RichTextBox>

// 获取RichTextBox的Document属性
TextPointer caretPosition = MyRichTextBox.CaretPosition;
TextPointerContext context = caretPosition.GetPointerContext(LogicalDirection.Backward);

// 如果光标位于一个Paragraph中
if (context == TextPointerContext.ElementStart)
{
    // 获取当前Paragraph
    Paragraph paragraph = caretPosition.Parent as Paragraph;

    // 设置选项卡大小
    double tabSize = 40; // 以像素为单位
    paragraph.SetValue(Paragraph.TextIndentProperty, tabSize);

    // 添加选项卡停靠位置
    List<double> tabStops = new List<double> { tabSize };
    paragraph.SetValue(Paragraph.TextIndentProperty, tabStops);
}