转载于(https://social.msdn.microsoft.com/Forums/windowsapps/zh-CN/af3161ce-f020-4b0b-9b84-95ae597e53fd/resourcedictionary-xclass-xaml-mouseleftbuttondown-xclass?forum=wpfzhchs)

在资源字典中设置listboxItem的鼠标左击的事件样式。

打出这段代码提示“ResourceDictionary”根元素需要 x:Class 特性来支持 XAML 文件中的事件处理程序。请移除 MouseLeftButtonDown 事件的事件处理程序，或将 x:Class 特性添加到根元素。 ”错误，

这句话是什么意思？难道EventSetter 不能在资源字典中写？

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

                    xmlns:local="clr-namespace:WpfApplication1">

    <Style x:Key="remenber" TargetType="{x:Type ListBoxItem}"  >

        <Setter Property="Margin" Value="1"></Setter>

<EventSetter Event="MouseLeftButtonDown"  Handler="ProjectMouseLeftButtonDown"/>

        <Style.Triggers>

            <Trigger Property="IsMouseOver" Value="True">

                <Setter Property="Background" Value="#FF569BEE"></Setter>

            </Trigger>

        </Style.Triggers>

    </Style>

</ResourceDictionary>

解决思路:

1.首先，EventSetter 是可以在资源字典中写的。那句提示意思是需要在ResourceDictionary标签内加上x:Class特性。

你可以写成这样：

ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

                    xmlns:local="clr-namespace:WpfApplication1"

                    x:Class="命名空间.资源字典的名称" >

</ResourceDictionary>

命名空间：以你的代码为例，此处应为”WpfApplication1”

资源字典的名称：如果资源字典文件是”Dictionary1.xaml”，这里就是”Dictionary1”

完整写法就是 x:Class=”WpfApplication1. Dictionary1”

2.下面的Demo供你参考：

Dictionary1.xaml：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

                    xmlns:local="clr-namespace:WriteEventInResourceDictionary"

                    x:Class="WriteEventInResourceDictionary.Dictionary1">

    <Style  TargetType="{x:Type ListBoxItem}" BasedOn="{StaticResource {x:Type ListBoxItem}}">

        <EventSetter Event="PreviewMouseLeftButtonDown" Handler="MyCustomMouseEvent"/>

    </Style>

</ResourceDictionary>

Dictionary1.xaml.cs:

namespace WriteEventInResourceDictionary

{

    public partial class Dictionary1

    {

        private void MyCustomMouseEvent(object sender, RoutedEventArgs e)

        {

            MessageBox.Show("Hello");

        }

    }

}

MainWindow.xaml:

<ListBox>

      <ListBoxItem>Item 1</ListBoxItem>

      <ListBoxItem>Item 2</ListBoxItem>

      <ListBoxItem>Item 3</ListBoxItem>

</ListBox>

App.xaml:

<Application x:Class="WriteEventInResourceDictionary.App"

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

             xmlns:local="clr-namespace:WriteEventInResourceDictionary"

             StartupUri="MainWindow.xaml">

    <Application.Resources>

        <ResourceDictionary>

            <ResourceDictionary.MergedDictionaries>

                <ResourceDictionary Source="Dictionary1.xaml" />

            </ResourceDictionary.MergedDictionaries>

        </ResourceDictionary>

    </Application.Resources>

</Application>