Change button border thickness in wpf?

Why the border thickness of the Button doesn't change?

If I change the border thickness to 1 or 100, it doesn't matters. It's the same. I would like to change it using Style, not Custom Template.

 <Window x:Class="GUI.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <Style x:Key="newYellowButton" TargetType="{x:Type Button}">
        <Setter Property="Width" Value="100"/>
        <Setter Property="Height" Value="100"/>
        <Setter Property="Background">
            <Setter.Value>
                <RadialGradientBrush Center="0.5,0.5" GradientOrigin="0.5,0.5" RadiusX="0.5" RadiusY="0.5" SpreadMethod="Pad" ColorInterpolationMode="SRgbLinearInterpolation">
                    <GradientStop Color="#FFEEEE3B" Offset="0.5" />
                    <GradientStop Color="#FFF0E49A" Offset="1" />
                </RadialGradientBrush>
            </Setter.Value>
        </Setter>
        <Setter Property="BorderThickness" Value="9"/>
        <Setter Property="BorderBrush" Value="Blue" />
        <Setter Property="Padding" Value="-4"/>
    </Style>
</Window.Resources>
<Grid>
    <Button Style="{StaticResource newYellowButton}" Content="Ok"/>
</Grid>

You can do it by changing the Button's ControlTemplate. Copy those style, brushes and ... to you resource dictionary then change the values you want.

To change the border thickness find the following code and make changes you want:

...
<Border 
      x:Name="Border"  
      CornerRadius="2" 
      BorderThickness="1"                             //CHANGE THIS VALUE
      Background="{StaticResource NormalBrush}"
      BorderBrush="{StaticResource NormalBorderBrush}">
      <ContentPresenter 
        Margin="2"
        HorizontalAlignment="Center"
        VerticalAlignment="Center"
        RecognizesAccessKey="True"/>
</Border>
...