Question

I have this xaml

<Button.Content>
  <Hyperlink>
    <Hyperlink.TextDecorations>
      <TextDecoration>
        <TextDecoration.Pen>
          <Pen Thickness="0" />
        </TextDecoration.Pen>
      </TextDecoration>
    </Hyperlink.TextDecorations>
    <Run Text="jumped over" />
  </Hyperlink>
</Button.Content>

I need to apply this from a style. My style looks like this

<Style x:Key="Button_Link" TargetType="{x:Type Hyperlink}">
  <Setter Property="TextDecorations" >
    <Setter.Value>
      <TextDecorations>
        <TextDecoration>
          <TextDecoration.Pen>
            <Pen Thickness="0" />
          </TextDecoration.Pen>
        </TextDecoration>
      </TextDecorations>
    </Setter.Value>
  </Setter>
</Style>

This is causing an error in my style file which is a ResourceDictionary used for loose XAML

I am applying the style to Hyperlink like this

Style="{DynamicResource Button_Link}"

Answer 1

You don’t need to set the pen thickness to zero to remove the underline you can using the following style:

<Style x:Key="Button_Link" TargetType="{x:Type Hyperlink}">            
     <Setter Property="TextDecorations" Value="None" />
</Style>

In case this is just a simplified example, you can fix your existing style by replacing <TextDecorations> with <TextDecorationsCollection> like so:

<Style x:Key="Button_Link" TargetType="{x:Type Hyperlink}">            
    <Setter Property="TextDecorations">
        <Setter.Value>
            <TextDecorationCollection>
                <TextDecoration>
                    <TextDecoration.Pen>
                        <Pen Thickness="0" />
                    </TextDecoration.Pen>
                </TextDecoration>
            </TextDecorationCollection>
        </Setter.Value>
    </Setter>
</Style>

Also, although not needed, your style is static so can be applied like

Style="{StaticResource Button_Link}"