Change Button Background when is not enabled

Question

I need to change my Button background (as SolidColorBrush for example) only when it is not enabled (IsEnabled == false).
How can I do?

Have I to modify the Button Style using the XAML or can I do this work programmatically? What is the correct XAML code, to change only the Background when it is not enabled?

I tried the following XAML code but it has no effect:

<Button>
<Button.Style>
    <Style TargetType="Button">
        <Style.Triggers>
            <Trigger Property="IsEnabled" Value="False">
                <Setter Property="Background" Value="Red"></Setter>
            </Trigger>
        </Style.Triggers>
    </Style>
</Button.Style>
</Button>

Answer 1

You can use a Style trigger:

<Image.Style>
    <Style>
        <Style.Triggers>
            <DataTrigger Binding="{Binding IsEnabled}" Value="False">
                <Setter Property="Image.Source" Value="pack://application:,,,/disabled.png" />
            </DataTrigger>
        </Style.Triggers>
    </Style>
</Image.Style>

Answer 2

You can change the background by editing the template. You'll find the default template for Button here.

In the trigger for IsEnabled you can simply add something like this:

<Setter Property="Background" Value="{StaticResource DisabledBackgroundBrush}"/>

EDIT: Try this instead then;

<Window.Resources>
    <Style TargetType="{x:Type Button}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border x:Name="Overlay" CornerRadius="2">
                        <ContentPresenter/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter TargetName="Overlay" Property="Background" Value="Red"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>
<StackPanel>
    <Button Content="Button" IsEnabled="False"/>
</StackPanel>

Just change it to suit your needs.