PopupWindow通过InteractionRequestTrigger（EventTrigger的派生类）侦听目标对象（InteractionRequest类型）的Raised事件Show出来；

<winInteractivity:Interaction.Triggers>  
    <prism:InteractionRequestTrigger SourceObject="{Binding Path=EmployeePopupViewRequest,Mode=OneWay}">  
        <prism:PopupWindowAction IsModal="True" CenterOverAssociatedObject="True">  
            <prism:PopupWindowAction.WindowContent>  
                <views:EmployeeView />  
            </prism:PopupWindowAction.WindowContent>  
        </prism:PopupWindowAction>  
    </prism:InteractionRequestTrigger>  
</winInteractivity:Interaction.Triggers>

PopupWindow实现IInteractionRequestAware接口，通过Action委托成员FinishInteraction关闭PopupWindow；

public Action FinishInteraction { get; set; }

public INotification Notification  
{  
    get  
    {  
        return this.DataContext as INotification;  
    }  
    set  
    {  
        this.DataContext = value;  
    }  
}

private void CloseWindow()  
{  
    if (this.FinishInteraction != null)  
        this.FinishInteraction();  
}

InteractionRequestedEventArgs（上述Raised事件的事件处理器的EventArgs）有两个主要成员，一个是INotification的派生类（将会作为PopupWindow的DataContext：即ViewModel），另一个是回调使用的Action委托。