下載System.Windows.Interactivity.dll檔案，並引入專案中（在VS專案的引用列表中可以看到）。可在Nuget搜尋System.Windows.Interactivity下載安裝到專案中。

XAML中使用該dll

 xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

<!-- TextBox控制元件的獲得焦點、失去焦點事件 -->
 

<TextBox Text="Test">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="LostFocus">
            <i:InvokeCommandAction Command="{Binding RelativeSource={RelativeSource AncestorType=Window},Path=DataContext.OnTextLostFocus}"
                                   CommandParameter
 
="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorLevel=1, AncestorType={x:Type TextBox}}}"/>
        </i:EventTrigger>
        <i:EventTrigger EventName="GotFocus">
            <i:InvokeCommandAction Command="{Binding RelativeSource={RelativeSource AncestorType=Window},Path=DataContext.OnTextGotFocus}
 
"
                                   CommandParameter="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorLevel=1, AncestorType={x:Type TextBox}}}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</TextBox>

由於VS中不支援System.Windows.Interactivity的智慧提示，經常要查閱這個EventTrigger還能觸發哪些方法，所有EventName的列表如下：

• MSDN中Grid Events https://msdn.microsoft.com/en-us/library/system.windows.controls.grid_events(v=vs.110).aspx