WPF-为什么我的财产没有更新？

Question

Here's some code:

<ListBox
    MaxWidth="468"
    SelectionMode="Extended"
    ItemsSource="{Binding Visitors, Mode=TwoWay}">
    <ListBox.ItemContainerStyle>
        <Style TargetType={x:Type ListBoxItem}>
            <Setter Property="IsSelected" Value="{Binding VisitorSelected, Mode=TwoWay}" />
        </Style>
    </ListBox.ItemContainerStyle>
</ListBox>

I need Visitors to be updated (at the source) whenever a visitor is selected. For some reason, What I have doesn't work. I'm racking my brain, but I can't think of a way around this. Ideas?

EDIT: Sorry, I accidentally had a duplicated property in there, which I removed. Also, let me clarify something: VisitorSelected IS getting updated. However it's not doing me much good, because I need to be notified in the view model containing Visitors - not where VisitorSelected is defined. I hope this makes sense

Answer 1

I ended up adding an Action parameter to the visitor item type, then calling that when VisitorSelected is set. The Action is passed in by the view model.