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>

Unlike the code in accepted answer this one allows using resource dictionary for styles. Shamelessly stolen from http://social.msdn.microsoft.com/forums/en-US/wpf/thread/3c66adb7-fd26-40c7-8404-85f6fefbd392/ answered by Vivien Ruitz

<!--App.xaml-->        <ResourceDictionary.MergedDictionaries>             <ResourceDictionary Source="/MyAppli;component/Resources/Themes/StyleDictionary.xaml"/>              <ResourceDictionary Source="/MyAppli;component/Resources/Themes/ApplyStyleDictionary.xaml"/>              ...          </ResourceDictionary.MergedDictionaries> <!--StyleDictionary.xaml-->        <ResourceDictionary.MergedDictionaries>             <ResourceDictionary Source="/PresentationFramework.Aero;V3.0.0.0;31bf3856ad364e35;component/themes/aero.normalcolor.xaml" />         </ResourceDictionary.MergedDictionaries>         <Style x:Key="ButtonStyleToApply" TargetType="Button" BasedOn="{StaticResource {x:Type Button}}" >             ...  <!--Extend the aero style here-->        </Style> <!--ApplyStyleDictionary.xaml-->        <Style TargetType="Button" BasedOn="{StaticResource ButtonStyleToApply}"/>