Why doesn't my implicit ContextMenu style override the TextBox context menu style?

Question

I have this implicit style for ContextMenuwhich I took from this site :

<Application.Resources>
        <SolidColorBrush x:Key="WindowBackgroundBrush" Color="#FFF" />
        <SolidColorBrush x:Key="SolidBorderBrush" Color="#888" />

        <Style TargetType="ContextMenu">
            <Setter Property="SnapsToDevicePixels" Value="True"/>
            <Setter Property="OverridesDefaultStyle" Value="True"/>
            <Setter Property="Grid.IsSharedSizeScope" Value="true"/>
            <Setter Property="HasDropShadow" Value="True"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ContextMenu">
                        <Border 
          Name="Border"
          Background="{StaticResource WindowBackgroundBrush}"
          BorderBrush="{StaticResource SolidBorderBrush}"
          BorderThickness="1" >
                            <StackPanel IsItemsHost="True"
                      KeyboardNavigation.DirectionalNavigation="Cycle"/>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="HasDropShadow" Value="true">
                                <Setter TargetName="Border" Property="Padding" Value="0,3,0,3"/>
                                <Setter TargetName="Border" Property="CornerRadius" Value="4"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Application.Resources>

Then I tried to use it here, so he applied for the default values ContextMenufor TextBoxand for ContextMenufor my Button.

  

</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <TextBox Height="30" Width="200">Test</TextBox>
    <Button Grid.Row="1" Width="200" Height="30" Content="Test2">
        <Button.ContextMenu>
            <ContextMenu>
                <MenuItem>Test</MenuItem>
                <MenuItem>Test2</MenuItem>
            </ContextMenu>
        </Button.ContextMenu>
    </Button>
</Grid>

The style applies to Button, but not to TextBox.

I believe this should be fairly simple and straightforward, why doesn't my implicit style apply to standard ones ContextMenu TextBox, what am I doing wrong?

== Update ==

, , , TextBox ContextMenu, , - . Snoop , ContextMenu , , EditorContextMenu, , . ? .

, . TextBox, . , ContextMenu, ApplicationCommands, :

<ContextMenu x:Key="DefaultContextMenu">
        <MenuItem Command="ApplicationCommands.Copy" />
        <MenuItem Command="ApplicationCommands.Cut" />
        <MenuItem Command="ApplicationCommands.Paste" />        
    </ContextMenu>

TextBoxStyle :

<Style x:Key="MyTextBoxStyle" TargetType="TextBox">
    <Setter Property="ContextMenu" Value="{StaticResource DefaultContextMenu}" />

TextBox Default ContextMenu .