Q:

refresh control style based on whether the file exists

I have the following xaml for displaying files.   If the file exists on the local machine, it's a clickable hyperlink, otherwise just a normal textblock. 
    <TextBlock Visibility="{Binding FileName, Converter={StaticResource fileExistsConverter}}" Grid. Column="2" TextDecorations="Underline" Margin="5,0,0,0" Foreground="Black" Text="{Binding FileName}" />
    <TextBlock Margin="5,0,0,0" Grid. Column="2" Visibility="{Binding FileName, Converter={StaticResource fileDoesntExistConverter}}">
        <Hyperlink Click="Hyperlink_Click_1">
            <TextBlock Text="{Binding FileName}" />
        </Hyperlink>
    </TextBlock>

This works on page load, but doesn't update when the window is open when for example one of the listed files is downloaded.   How would I go about triggering a refresh so the XAML can swap the styles? 

A:

resources : 
   <Style x:Key="SwapTemplateStyle" TargetType="ContentControl">

       <Setter Property="Template">
            <Setter. Value>
                <ControlTemplate TargetType="ContentControl">
                    <TextBlock />
                </ControlTemplate>                                                       
            </Setter. Value>
        </Setter>

        <Style. Triggers>
            <DataTrigger Binding="{Binding IsExist}" Value="True">
                <Setter Property="Template">
                    <Setter. Value>
                        <ControlTemplate TargetType="ContentControl">                                
                              <Hyperlink>
                                 <TextBlock />
                              </Hyperlink>
                        </ControlTemplate>
                    </Setter. Value>
                </Setter>
            </DataTrigger>                
        </Style. Triggers>
   </Style>

in your view :
        <ContentControl Style="{StaticResource SwapTemplateStyle}" />

