Make text to have background + border

If I have a label with its content "White, Yellow, Black" and I want to make "yello开发者_JAVA技巧w" to have a white background color + border with black line around the word "Yellow".

What XAML code is needed?

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You need to split the content:

<Label>
    <StackPanel Orientation="Horizontal">
        <TextBlock Text="White, "/>
        <Border BorderBrush="Black" BorderThickness="1">
            <TextBlock Background="White" Text="Yellow"/>
        </Border>
        <TextBlock Text=", Black"/>
    </StackPanel>
</Label>

(If this is not what you want you should express yourself more clearly)