MultiBinding的StringFormat参数问题

在wpf的绑定中，我们会用到多值绑定，如下：

<MultiBinding Mode="OneWay" StringFormat="{3}({0}/{1})：{2}">
        <Binding Path="CurIndex" Mode="OneWay"></Binding>
        <Binding Path="TotalCount" Mode="OneWay"></Binding>
        <Binding Path="CurName" Mode="OneWay"></Binding>
        <Binding Path="AreaName" Mode="OneWay"></Binding>
</MultiBinding>

这里如果

StringFormat="{3}({0}/{1})：{2}"这样写是不能通过编译器的，解决方案是在前面加一组大括号就可以了，如下：

StringFormat="{}{3}({0}/{1})：{2}"

完整绑定如下：

<TextBlock.Text>
          <MultiBinding Mode="OneWay" StringFormat="{}{3}({0}/{1})：{2}">
          <Binding Path="CurIndex" Mode="OneWay"></Binding>
          <Binding Path="TotalCount" Mode="OneWay"></Binding>
          <Binding Path="CurName" Mode="OneWay"></Binding>
           <Binding Path="AreaName" Mode="OneWay"></Binding>
           </MultiBinding>
</TextBlock.Text>