Button foreground doesn't change when content is StackPanel

I have a button style defined where the template has a ContentPresenter with a name of "contentPresenter". It then has a trigger set up like this:

<ControlTemplate.Triggers>
    <Trigger Property="UIElement.IsEnabled" Value="False">
        <Setter Property="TextElement.Foreground" TargetName="contentPresenter" Value="#FF838383" />
    </Trigger>
</ControlTemplate.Triggers>

This trigger simply changes the foreground color of a button to gray when the button is disabled. However, I have one button in my application which does not have simple text as its content. The button looks like this:

<Button Grid.Column="3" Grid.Row="3" Grid.ColumnSpan="2"
            Margin="120 20 30 10"
            Command="{Binding SomeCommand}">
        <StackPanel Orientation="Horizontal">
            <Image Source="{Binding MyImage}" Margin="0 0 2 0"
                   Visibility="{Binding ShowMyImage, Converter={StaticResource BooleanToVisibilityConverter}}"/>
            <TextBlock Text="{Binding ButtonText}" />
        </StackPanel>
    </Button>

The foreground of this button is always the same whether the button is disabled or not. I'm thinking it's because the text for the button is in a textblock within the stackpanel in the content presenter, but I don't know how to get the foreground color changes to be applied to the inner textblock.

I tried changing the Property in the trigger to use "TextBlock.Foreground" instead of "TextElement.Foreground". I also tried binding the Foreground of the inner textblock to the foreground color of the closest ancestor of type FrameworkElement like this:

<TextBlock Text="{Binding ButtonText}" Foreground="{Binding RelativeSource={RelativeSource AncestorType={x:Type FrameworkElement}}, Path=(FrameworkElement.Foreground)}" />

None of this worked. What do I need to do to get the foreground color to apply to the TextBlock inside the StackPanel?

Your trigger should be in the Style, and should be setting Foreground on the Button itself, rather than on the ContentPresenter. Then it'll Just Work, with a custom template or with the default template. No need for any extra bindings.

<Style TargetType="Button" x:Key="MyButtonStyle">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Border Background="Beige" BorderBrush="Black" BorderThickness="1" Padding="6,2">
                    <ContentPresenter 
                        />
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Style.Triggers>
        <Trigger Property="IsEnabled" Value="False">
            <Setter Property="Foreground" Value="#FF838383" />
        </Trigger>
    </Style.Triggers>
</Style>

Usage:

<Button
    IsEnabled="False"
    Style="{StaticResource MyButtonStyle}"
    >
    <StackPanel>
        <TextBlock 
        >Blah Blah</TextBlock>
        <Button>X</Button>
    </StackPanel>
</Button>
<Button Style="{StaticResource MyButtonStyle}" IsEnabled="False">Testing</Button>

Screenshot (never mind my ugly template):