我正在尝试在添加到 TextBox ControlTemplate 的清除按钮的单击事件上清除 TextBox 的文本：
<Window x:Class="WpfApp1.TextBoxClearing"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApp1"
mc:Ignorable="d"
Title="TextBoxClearing" Height="300" Width="300">
<Window.Resources>
<SolidColorBrush x:Key="TextBox.Static.Border" Color="#FFE2E3EA"/>
<SolidColorBrush x:Key="TextBox.MouseOver.Border" Color="#FFC5DAED"/>
<SolidColorBrush x:Key="TextBox.Focus.Border" Color="#FFB5CFE7"/>
<Style x:Key="TextBoxStyle1" TargetType="{x:Type TextBox}">
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
<Setter Property="BorderBrush" Value="{StaticResource TextBox.Static.Border}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="KeyboardNavigation.TabNavigation" Value="None"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="AllowDrop" Value="true"/>
<Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<ControlTemplate.Resources>
<Storyboard x:Key="OnMouseLeftButtonDown1">
<!-- Storyboard.TargetProperty="(TextBlock.Text)" Storyboard.TargetName="PART_ContentHost"-->
<StringAnimationUsingKeyFrames Storyboard.TargetProperty="Text"
Storyboard.Target="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type TextBox}}}" >
<DiscreteStringKeyFrame KeyTime="0:0:0.0" Value=""/>
</StringAnimationUsingKeyFrames>
</Storyboard>
</ControlTemplate.Resources>
<Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
<DockPanel>
<Button x:Name="MYPART_Clear" DockPanel.Dock="Right">X</Button>
<ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden" RenderTransformOrigin="0.5,0.5" />
</DockPanel>
</Border>
<ControlTemplate.Triggers>
<EventTrigger RoutedEvent="UIElement.MouseLeftButtonDown" SourceName="MYPART_Clear">
<BeginStoryboard Storyboard="{StaticResource OnMouseLeftButtonDown1}"/>
</EventTrigger>
<Trigger Property="Text" Value="">
<Setter TargetName="MYPART_Clear" Property="Visibility" Value="Collapsed" />
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Opacity" TargetName="border" Value="0.56"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.MouseOver.Border}"/>
</Trigger>
<Trigger Property="IsKeyboardFocused" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.Focus.Border}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsInactiveSelectionHighlightEnabled" Value="true"/>
<Condition Property="IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="SelectionBrush" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
</MultiTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
<Grid>
<TextBox VerticalAlignment="Center" HorizontalAlignment="Center" Width="150" Style="{DynamicResource TextBoxStyle1}"></TextBox>
</Grid>
一切似乎在逻辑上都很好，但我不明白为什么它不能清除文本。我曾尝试通过其名称（PART_ContentHost）访问元素或找到父 TextBox，但它们都处于风向标。
它可以通过纯 XAML 实现吗？我不喜欢安装 Blend SDK。使用这些主要工具应该可以做到这一点。不需要任何 Nuget 安装的自定义 ActionTriger 也可以。
请注意，类似问题的答案需要安装 Nuget，这对我来说并不理想。
