Override default styling in WPF TextBox, based on PresentationFramework.Aero

It seems to work if you put the Style as a lower-level resource, instead of in the same ResourceDictionary:

<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/PresentationFramework.Aero, Version=3.0.0.0, Culture=Neutral, PublicKeyToken=31bf3856ad364e35, ProcessorArchitecture=MSIL;component/themes/aero.normalcolor.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Grid.Resources>
    <Border BorderBrush="Blue" BorderThickness="3">
        <Border.Resources>
            <Style TargetType="{x:Type TextBox}" BasedOn="{StaticResource {x:Type TextBox}}">
                <Setter Property="Margin" Value="2" />
                <Setter Property="Padding" Value="2" />
            </Style>
        </Border.Resources>
        <TextBox />
    </Border>
</Grid>