自定义附加属性的绑定
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="Property">
<Setter.Value>
<MultiBinding Converter="{StaticResource MultiBinding}">
<Binding Path="(local:CustomAttachedProperty)" />
</MultiBinding>
</Setter.Value>
</Setter>
</Style>
不要忘记()要不就是UnsetValue 悲剧啊